Add Gerrit 3.13.7

Change-Id: I956173b93445d0a90e620fc86bdf039d7cfc5a5a

gerrit@3.13.7.rb

diff --git a/gerrit@3.13.7.rb b/gerrit@3.13.7.rb
new file mode 100644
index 0000000..a952151
--- /dev/null
+++ b/gerrit@3.13.7.rb
@@ -0,0 +1,17 @@
+# typed: false
+# frozen_string_literal: true
+
+require_relative "./gerritbase"
+
+class GerritAT3137 < GerritBase
+  def self.java_version
+    "21"
+  end
+
+  set_common_dependencies
+
+  version "3.13.7"
+  sha256 "b832b81ed03bffaf3f7ef7a980394e90e57ac256c010ec5c93d8d2cdc556d8a9"
+  url generate_url(version)
+
+end