Bump google-cloud-core from 0.28.1 to 2.2.1

Bumps [google-cloud-core](https://github.com/googleapis/python-cloud-core) from 0.28.1 to 2.2.1.
- [Release notes](https://github.com/googleapis/python-cloud-core/releases)
- [Changelog](https://github.com/googleapis/python-cloud-core/blob/main/CHANGELOG.md)
- [Commits](https://github.com/googleapis/python-cloud-core/compare/v0.28.1...v2.2.1)

---
updated-dependencies:
- dependency-name: google-cloud-core
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -6,7 +6,7 @@ elasticsearch==6.3.1
 falcon==1.4.1
 google-api-core==1.5.1
 google-auth==1.5.1
-google-cloud-core==0.28.1
+google-cloud-core==2.2.1
 google-cloud-datastore==1.7.1
 googleapis-common-protos==1.5.3
 grpcio==1.16.0