Missed a couple places to set READTHEDOCS_LANGUAGE (#5951)

Not sure how I missed this.
This should cause us to have proper env vars in builds

Author: ericholscher

readthedocs/projects/tasks.py

@@ -649,6 +649,7 @@ def get_env_vars(self):
             'READTHEDOCS': True,
             'READTHEDOCS_VERSION': self.version.slug,
             'READTHEDOCS_PROJECT': self.project.slug,
+            'READTHEDOCS_LANGUAGE': self.project.language,
         }
 
         if self.config.conda is not None:

readthedocs/rtd_tests/tests/test_builds.py

@@ -341,6 +341,7 @@ def test_get_env_vars(self):
             'READTHEDOCS': True,
             'READTHEDOCS_VERSION': version.slug,
             'READTHEDOCS_PROJECT': project.slug,
+            'READTHEDOCS_LANGUAGE': project.language,
             'BIN_PATH': os.path.join(
                 project.doc_path,
                 'envs',