Update release template following v0.55.0 (#4055)

* Drop distinction between engine and browser

* Adapt instructions to new branching and versioning strategy

.github/ISSUE_TEMPLATE/release.md

@@ -13,10 +13,9 @@ labels: ["release"]
 
 ### At the beginning of the cycle
 
-- [ ] Obtain the Release coordinator's contact from the `@k6-browser` team and co-assign the issue to them.
-- [ ] Create a new `release-v0.5x.0` long-lived branch and add a new release notes file using the available [template](https://github.com/grafana/k6/blob/master/release%20notes/template.md) to the [repository's `release notes` folder](https://github.com/grafana/k6/blob/master/release%20notes).
+- [ ] Create a new `release-v{major}.{minor}.0` branch and add a new release notes file using the available [template](https://github.com/grafana/k6/blob/master/release%20notes/template.md) to the [repository's `release notes` folder](https://github.com/grafana/k6/blob/master/release%20notes).
 - [ ] Go through the potential [dependencies updates](https://github.com/grafana/k6/blob/master/Dependencies.md) and create a dedicated PR if any of them is relevant to this release.
-- [ ] Create a new `release-v0.5x.0` long-lived branch on the [grafana/k6-DefinitelyTyped](https://github.com/grafana/k6-DefinitelyTyped) fork repository.
+- [ ] Create a new `release-v{major}.{minor}.0` branch on the [grafana/k6-DefinitelyTyped](https://github.com/grafana/k6-DefinitelyTyped) fork repository.
     - [ ] Bump the version in [types/k6/package.json](https://github.com/grafana/k6-DefinitelyTyped/blob/master/types/k6/package.json#L4) to the next one.
 
 ### Release Preparation
@@ -32,9 +31,9 @@ labels: ["release"]
 - [ ] Ensure all pull-requests in the `k6-docs` repository, related to new or modified functionalities introduced by the new version have been created.
 - [ ] Ensure all PRs in the k6 repository, part of the current [milestone](https://github.com/grafana/k6/milestones), have been merged.
 - [ ] Open a PR with the release notes for the new version
-  - [ ] Ask teams who might have contributed to the release (k6-browser, k6-ecosystem, k6-docs, k6-devrel teams, etc.) to contribute their notes and review the existing ones.
+  - [ ] Ask teams who might have contributed to the release (k6-ecosystem, k6-docs, k6-devrel teams, etc.) to contribute their notes and review the existing ones.
   - [ ] Remember to mention and thank [external contributors](https://github.com/search?q=user%3Agrafana+repo%3Ak6+milestone%3A%22v0.51.0%22+-author%3Amstoykov+-author%3Aoleiade+-author%3Ana--+-author%3Acodebien+-author%3Aolegbespalov+-author%3Aandrewslotin+-author%3Ajoanlopez+-author%3Aankur22+-author%3Ainancgumus+-author%3Aszkiba+-author%3Adependabot%5Bbot%5D&type=pullrequests). <-- Update the query with the correct milestone version.
-- [ ] Share the release notes PR with the k6 open-source teams. Request contributions from all affected teams (k6-browser, k6-chaos, k6-docs, k6-devrel, etc.) and any other stakeholders involved in the new release.
+- [ ] Share the release notes PR with the k6 open-source teams. Request contributions from all affected teams (k6-chaos, k6-docs, k6-devrel, etc.) and any other stakeholders involved in the new release.
 - [ ] Open a separate pull-request for bumping [the k6 Go project's version](https://github.com/grafana/k6/blob/master/lib/consts/consts.go#L11-L12).
 - [ ] Open a PR in the `DefinitelyTyped/DefinitelyTyped` repository, using the release branch created in the grafana/k6-DefinitelyTyped fork, to update the k6 type definitions for the new release.
 
@@ -46,15 +45,16 @@ labels: ["release"]
 
 #### Documentation
 
-- [ ] Open and merge a pull-request from `main` in the `k6-docs` repository, copying the current k6's `next` to a folder named with the k6 version (e.g. `v0.48.x`).
+- [ ] Open and merge a pull-request from `main` in the `k6-docs` repository, copying the current k6's `next` to a folder named with the k6 version (e.g. `v0.55.x`).
 - [ ] Ensure the k6 repository release notes PR contains the correct links to the docs.
 
 #### In k6 repository
 
 - [ ] Merge the PR bumping [the k6 Go project's version](https://github.com/grafana/k6/blob/master/lib/consts/consts.go#L11-L12).
 - [ ] Merge the release notes PR.
 - [ ] Pull locally the previously merged changes.
-- [ ] Create and push a new tag of the form `vX.Y.Z` using git: `git tag v0.5x.0 -m "v0.5x.0"`.
+- [ ] Create a new long-lived `v{major}.{minor}.x` release branch from the `main` branch.
+- [ ] Checkout the new `v{major}.{minor}.x` release branch, create and push a new tag of the form `v{major}.{minor}.0` using git: _e.g._ `git tag v0.55.0 -m "v0.55.0"`.
 
 #### Announcements