Upgrade go to 1.21 (#15)

.github/workflows/go.yml

@@ -5,10 +5,10 @@ jobs:
     name: Build
     runs-on: ubuntu-latest
     steps:
-      - name: Set up Go 1.13
+      - name: Set up Go 1.21
         uses: actions/setup-go@v1
         with:
-          go-version: 1.13
+          go-version: 1.21
         id: go
 
       - uses: actions/checkout@v1

go.mod

@@ -0,0 +1,5 @@
+module github.com/jacobtomlinson/gha-anaconda-package-version
+
+go 1.21.6
+
+require github.com/coreos/go-semver v0.3.1

go.sum

@@ -0,0 +1,5 @@
+github.com/coreos/go-semver v0.3.1 h1:yi21YpKnrx1gt5R+la8n5WgS0kCrsPp33dmEyHReZr4=
+github.com/coreos/go-semver v0.3.1/go.mod h1:irMmmIw/7yzSRPWryHsK7EYSg09caPQL03VsM8rvUec=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=