Update google-cloud-translate requirement

Updates the requirements on [google-cloud-translate](https://github.com/googleapis/python-translate) to permit the latest version.
- [Release notes](https://github.com/googleapis/python-translate/releases)
- [Changelog](https://github.com/googleapis/python-translate/blob/master/CHANGELOG.md)
- [Commits](googleapis/python-translate@v2.0.1...v3.0.0)

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

requirements-optional.txt

@@ -12,7 +12,7 @@ django-auth-ldap>=1.3.0,<2.3.0
 # Gerrit
 git-review>=1.27.0
 # Google
-google-cloud-translate>=2.0.1,<2.1.0
+google-cloud-translate>=2.0.1,<3.1.0
 # INI
 iniparse==0.5
 # Mercurial