chore: add upload of release artifacts to GitHub releases

Author: CaerusKaru

.github/workflows/main.yaml

@@ -599,7 +599,28 @@
                "if": "matrix.host.upload",
                "name": "Push container sync_jwks_to_configmap:sync_jwks_to_configmap",
                "run": "bazel run --stamp //cmd/sync_jwks_to_configmap:sync_jwks_to_configmap_container_push"
-            }
+            },
+            {
+               "if": "matrix.host.upload",
+               "name": "Download release artifacts",
+               "uses": "actions/download-artifact@v4",
+               "with": {
+                  "merge-multiple": true
+               }
+            },
+            {
+               "if": "matrix.host.upload",
+               "name": "Calculate shasum",
+               "run": "shasum -a 256 assets/* > sha256"
+            },
+            {
+               "if": "matrix.host.upload",
+               "name": "Create GitHub draft release and upload artifacts",
+               "uses": "softprops/action-gh-release@v2",
+               "with": {
+                  "files": [ "assets/*", "sha256" ]
+               }
+            },
          ],
          "strategy": {
             "matrix": {