Add missing "Implementation-Vendor" in manifest with bazel build

Change-Id: Id21ef6740b021db408b272291f02dc7a083e125e
diff --git a/BUILD b/BUILD
index 3a69de5..dcf1f80 100644
--- a/BUILD
+++ b/BUILD
@@ -14,6 +14,7 @@
         "Gerrit-Module: com.ericsson.gerrit.plugins.projectgroupstructure.Module",
         "Implementation-Title: project-group-structure plugin",
         "Implementation-URL: https://gerrit-review.googlesource.com/#/admin/projects/plugins/project-group-structure",
+        "Implementation-Vendor: Ericsson",
     ],
     resources = glob(["src/main/resources/**/*"]),
 )