Add github to prepackaged plugins. (#11042)

Makefile

@@ -76,6 +76,7 @@ TE_PACKAGES=$(shell go list ./...|grep -v plugin_tests)
 # Plugins Packages
 PLUGIN_PACKAGES=mattermost-plugin-zoom-v1.0.6
 PLUGIN_PACKAGES += mattermost-plugin-autolink-v1.0.0
+PLUGIN_PACKAGES += mattermost-plugin-github-v0.10.0
 PLUGIN_PACKAGES += mattermost-plugin-welcomebot-v1.0.0
 PLUGIN_PACKAGES += mattermost-plugin-aws-SNS-v1.0.0
 PLUGIN_PACKAGES += mattermost-plugin-jira-v2.0.0