chore: go down to rc.1 so that the stage-release script works (#16135)

Author: jelbourn

package.json

@@ -28,7 +28,7 @@
     "preinstall": "node ./tools/npm/check-npm.js",
     "format": "git-clang-format HEAD $(git diff HEAD --name-only | grep -v \"\\.d\\.ts\")"
   },
-  "version": "8.0.0",
+  "version": "8.0.0-rc.1",
   "requiredAngularVersion": "^8.0.0 || ^9.0.0-0",
   "requiredMDCVersion": "^1.1.0",
   "dependencies": {