fix(release-please): uses alternate approach to find files in repo (#198)

Refs https://github.com/googleapis/release-please/blob/master/CHANGELOG.md#930-2021-01-22

Author: Benjamin E. Coe

package-lock.json

@@ -26,7 +26,7 @@
   "homepage": "https://github.com/bcoe/release-please-action#readme",
   "dependencies": {
     "@actions/core": "^1.2.6",
-    "release-please": "^9.3.0-candidate.1"
+    "release-please": "^9.3.0"
   },
   "devDependencies": {
     "@zeit/ncc": "^0.22.3",