Generate Inventory & Sha7 appended filenames for JRuby

Currently the Ruby buildapack is tightly coupled to the URLs that are generated by this repo. I am in the process of introducing an inventory file that the buildpack can use as a lookup. To start that process this commit introduces generating tgz files with the first 7 SHA256 characters appended. This allows us to update the same version number in the future without worrying that it will break future digest checks of the URL.

With this change the builder will continue to generate the original URLs, but it will also generate "<filename>-<sha256>.tgz" files as well and append this information to a `jruby_inventory.toml` file.

.github/workflows/build_jruby.yml

@@ -51,3 +51,13 @@ jobs:
       - name: Upload Ruby runtime archive to S3 production
         if: (!inputs.dry_run)
         run: aws s3 sync ./output "s3://${S3_BUCKET}"
+
+  after-build-and-upload:
+    needs: build-and-upload
+    runs-on: pub-hk-ubuntu-24.04-xlarge
+    steps:
+      - name: Update Jruby inventory file locally
+        uses: peter-evans/create-pull-request@v6
+        with:
+          path: jruby_inventory.toml
+          title: "Add JRuby ${{inputs.jruby_version}} to inventory"