chore: remove last vestiges of gren

Author: justinedelson

package.json

@@ -77,8 +77,6 @@
     "lint-fix": "eslint src test e2e --fix",
     "test": "npm run unit-tests",
     "unit-tests": "jest --ci",
-    "update-release": "gren release --override",
-    "update-changelog": "gren changelog -G --override && sed -i '' 's+# Changelog+---+' CHANGELOG.md && awk 'BEGIN{print\"\"}1' CHANGELOG.md > CHANGELOG-premerge.md && sed -n 'p' CHANGELOG-add.md CHANGELOG-premerge.md > CHANGELOG.md && rm CHANGELOG-add.md && rm CHANGELOG-premerge.md",
     "prepack": "oclif-dev manifest && oclif-dev readme",
     "postpack": "rm -f oclif.manifest.json",
     "version": "oclif-dev readme && git add README.md",