gitlab: 13.5.1 -> 13.6.0

Changed ruby version to 2.7.x to match upstream.
Added a gem config for gitlab-pg_query as it tries to download a source
tarball during the build process.
Also removed a patch for gitaly that has become obsolete by upstream fix
[here](https://gitlab.com/gitlab-org/gitaly/-/commit/de04077c25cc23b001317d2efdf5a9ead0bc86b9).

pkgs/applications/version-management/gitlab/gitaly/default.nix

@@ -19,22 +19,16 @@ let
       };
   };
 in buildGoPackage rec {
-  version = "13.5.1";
+  version = "13.6.0";
   pname = "gitaly";
 
   src = fetchFromGitLab {
     owner = "gitlab-org";
     repo = "gitaly";
     rev = "v${version}";
-    sha256 = "1vkifmp56lkgj178na7pqd5h9yxffcy78yaz7ykd4rmgi4c8ayk8";
+    sha256 = "1b3vjg5sxrg8cfxn1nh8j26h847kxrfnn2chbb5v3ivhp1kp6zh2";
   };
 
-  # Fix a check which assumes that hook files are writeable by their
-  # owner.
-  patches = [
-    ./fix-executable-check.patch
-  ];
-
   goPackagePath = "gitlab.com/gitlab-org/gitaly";
 
   passthru = {
@@ -48,7 +42,7 @@ in buildGoPackage rec {
 
   postInstall = ''
     mkdir -p $ruby
-    cp -rv $src/ruby/{bin,lib,proto,git-hooks,gitlab-shell} $ruby
+    cp -rv $src/ruby/{bin,lib,proto,git-hooks} $ruby
   '';
 
   outputs = [ "out" "ruby" ];