Move prerelease tag making into separate workflow

Previously, the prerelease tag would be created when the prerelease PR
was opened. This means that changes to the agent after the prerelease PR
was opened would not be reflected in the tag used for validation with
internal apps.

Author: kaylareopelle

.github/workflows/prerelease.yml

@@ -42,14 +42,4 @@ jobs:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         TITLE: "Prerelease ${{env.prerelease_tag}}"
         BODY: "Updates the version number, changelog, and newrelic.yml (if it needs updating). This is an automated PR."
-        LABEL: prerelease
-
-    - name: Create pre release tag
-      uses: softprops/action-gh-release@a06a81a03ee405af7f2048a818ed3f03bbf83c7b # tag v2.5.0
-      with:
-        tag_name: ${{ env.prerelease_tag }}
-        name: ${{ env.prerelease_tag }}
-        target_commitish: prerelease_updates_${{ env.prerelease_tag }}
-        prerelease: true
-      env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        LABEL: prerelease

.github/workflows/prerelease_tag.yml

@@ -0,0 +1,34 @@
+name: Create Release PR
+
+on:
+  pull_request:
+    types:
+      - closed
+
+jobs:
+  create_prerelease_tag:
+    if: ${{ (github.event.pull_request.merged == true) && (contains(github.event.pull_request.labels.*.name, 'prerelease')) }}
+    runs-on: ubuntu-22.04
+    steps:
+    - name: Install Ruby 3.4
+      uses: ruby/setup-ruby@8d27f39a5e7ad39aebbcbd1324f7af020229645c # tag v1.287.0
+      with:
+        ruby-version: 3.4
+
+    - name: Checkout code
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # tag v6.0.2
+
+    - run: bundle install
+
+    - name: Set prerelease tag env var
+      run: echo "prerelease_tag=$(bundle exec rake newrelic:version:current)-pre" >> $GITHUB_ENV
+
+    - name: Make tag
+      uses: softprops/action-gh-release@a06a81a03ee405af7f2048a818ed3f03bbf83c7b # tag v2.5.0
+      with:
+        tag_name: ${{ env.prerelease_tag }}
+        name: ${{ env.prerelease_tag }}
+        target_commitish: prerelease_updates_${{ env.prerelease_tag }}
+        prerelease: true
+      env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}