fix(package): update @semantic-release/github back to a build from the beta branch

* Only the beta channel that is compatible with semantic-release v16
* 5.4.0-beta.1 worked, but subsequently v5.4.3 was released from master but didn't include the changes from the beta branch and  5.4.0-beta.1.

package.json

@@ -21,7 +21,7 @@
   "dependencies": {
     "@semantic-release/commit-analyzer": "^7.0.0-beta.1",
     "@semantic-release/error": "^2.2.0",
-    "@semantic-release/github": "^5.4.0-beta.1",
+    "@semantic-release/github": "=5.5.0-beta.1",
     "@semantic-release/npm": "^5.2.0-beta.5",
     "@semantic-release/release-notes-generator": "^7.1.2",
     "aggregate-error": "^2.0.0",