Revert "Update offline-github-changelog to version 2.0.0"

It brings in ejs 3, which breaks the documentation site :(

This reverts commit 27ed2b3.

Author: papandreou

package.json

@@ -69,7 +69,7 @@
     "magicpen": "^6.0.2",
     "mocha": "^8.2.1",
     "nyc": "^15.0.0",
-    "offline-github-changelog": "^2.0.0",
+    "offline-github-changelog": "^1.2.0",
     "prettier": "~2.1.0",
     "rollup": "^2.0.2",
     "rollup-plugin-commonjs": "^10.0.0",