Recursive create the pkgname directory when creating a release tarball

This step without the '-p' works fine for regular releases but it can
fail if the CI is running when this file changes or on a branch
matching 'patch/ci-release-*'.

.github/workflows/release.yml

@@ -255,7 +255,7 @@ jobs:
                   exe=".exe"
               fi
               pkgname=helix-$GITHUB_REF_NAME-$platform
-              mkdir $pkgname
+              mkdir -p $pkgname
               cp $source/LICENSE $source/README.md $pkgname
               mkdir $pkgname/contrib
               cp -r $source/contrib/completion $pkgname/contrib