Fetch avatar-gravatar plugin from its own stable-3.0 branch

The avatar-gravatar plugin has now a stable-3.0 branch
and should be fetched accordingly.

Change-Id: Iafb5b22989a7c3180e59782f1f05ebd13d6b1ce8
diff --git a/fpm/Makefile b/fpm/Makefile
index 175af5d..a83e75e 100644
--- a/fpm/Makefile
+++ b/fpm/Makefile
@@ -24,7 +24,7 @@
 LIBS_JOBS= \
   plugin-out-of-the-box-bazel-master-stable-3.0/lastSuccessfulBuild/artifact/bazel-bin/plugins/out-of-the-box/out-of-the-box.jar
 PLUGINS_JOBS= \
-  plugin-avatars-gravatar-bazel-master-stable-3.0/lastSuccessfulBuild/artifact/bazel-bin/plugins/avatars-gravatar/avatars-gravatar.jar \
+  plugin-avatars-gravatar-bazel-stable-3.0/lastSuccessfulBuild/artifact/bazel-bin/plugins/avatars-gravatar/avatars-gravatar.jar \
   plugin-uploadvalidator-bazel-stable-3.0/lastSuccessfulBuild/artifact/bazel-bin/plugins/uploadvalidator/uploadvalidator.jar
 
 RPM_OUT=$(OUT)/gerrit-$(VERSION)-$(RELEASE).$(BUILD_ARCH).rpm