feat: save pre-release charts in CI

Author: khvn26

.github/workflows/lint-test.yaml

@@ -50,3 +50,15 @@ jobs:
 
       - name: Run chart-testing (install)
         run: ct install --config ct.yaml
+
+      - id: get-version
+        run: |
+          echo version=$(helm show chart ./charts/flagsmith | grep -oP '^version: \K.*')-a$(date +"%Y%m%d%H%M%S") >> $GITHUB_OUTPUT
+
+      - run: helm package ./charts/flagsmith --version ${{ steps.get-version.outputs.version }} --destination out
+
+      - name: Save the chart archive
+        uses: actions/upload-artifact@v3
+        with:
+          name: flagsmith-${{ steps.get-version.outputs.version }}.tgz
+          path: out/flagsmith-${{ steps.get-version.outputs.version }}.tgz