ci: update charts version on docker image release (#3148)

.github/workflows/platform-docker-publish-image.yml

@@ -51,3 +51,25 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           context: .
+
+      - name: Set up release tag variables
+        run: |
+          TAG=${{github.ref_name}}
+          echo "version_trim=${TAG#v}" >> $GITHUB_ENV
+
+      - name: Update flagsmith-charts values.yaml with latest docker version
+        uses: fjogeleit/yaml-update-action@main
+        with:
+          token: ${{ secrets.FLAGSMITH_CHARTS_GITHUB_TOKEN }}
+          repository: flagsmith/flagsmith-charts
+          workDir: chart
+          masterBranchName: 'main'
+          targetBranch: 'main'
+          branch: docker-image-version-bump-${{ env.version_trim }}
+          commitChange: true
+          createPR: true
+          message: 'Flagsmith docker image version bump'
+          description: 'Automated PR generated by a release event in https://github.com/Flagsmith/flagsmith'
+          valueFile: 'charts/flagsmith/Chart.yaml'
+          value: ${{ env.version_trim }}
+          propertyPath: 'appVersion'