gradle: Pin pkgs to Gradle 6 that fail with 7

pkgs/applications/networking/p2p/frostwire/default.nix

···
-{ lib, stdenv, fetchFromGitHub, gradle, perl, jre, makeWrapper, makeDesktopItem, mplayer }:
+{ lib, stdenv, fetchFromGitHub, gradle_6, perl, jre, makeWrapper, makeDesktopItem, mplayer }:
 
 let
   version = "6.6.7-build-529";
···
   deps = stdenv.mkDerivation {
     name = "${name}-deps";
     inherit src;
-    buildInputs = [ gradle perl ];
+    buildInputs = [ gradle_6 perl ];
     buildPhase = ''
       export GRADLE_USER_HOME=$(mktemp -d)
       ( cd desktop
···
   inherit name src;
 
   nativeBuildInputs = [ makeWrapper ];
-  buildInputs = [ gradle ];
+  buildInputs = [ gradle_6 ];
 
   buildPhase = ''
     export GRADLE_USER_HOME=$(mktemp -d)

pkgs/development/tools/scenebuilder/default.nix

···
 { lib, stdenv, fetchFromGitHub, jdk, gradleGen, makeDesktopItem, copyDesktopItems, perl, writeText, runtimeShell, makeWrapper, glib, wrapGAppsHook }:
 let
   # The default one still uses jdk8 (#89731)
-  gradle = (gradleGen.override (old: { java = jdk; })).gradle_latest;
+  gradle = (gradleGen.override (old: { java = jdk; })).gradle_6_8;
 
   pname = "scenebuilder";
   version = "15.0.1";

pkgs/games/shattered-pixel-dungeon/default.nix

···
 , makeWrapper
 , fetchFromGitHub
 , nixosTests
-, gradle
+, gradle_6
 , perl
 , jre
 , libpulseaudio
···
   deps = stdenv.mkDerivation {
     pname = "${pname}-deps";
     inherit version src postPatch;
-    nativeBuildInputs = [ gradle perl ];
+    nativeBuildInputs = [ gradle_6 perl ];
     buildPhase = ''
       export GRADLE_USER_HOME=$(mktemp -d)
       # https://github.com/gradle/gradle/issues/4426
···
 in stdenv.mkDerivation rec {
   inherit pname version src postPatch;
 
-  nativeBuildInputs = [ gradle perl makeWrapper ];
+  nativeBuildInputs = [ gradle_6 perl makeWrapper ];
 
   buildPhase = ''
     export GRADLE_USER_HOME=$(mktemp -d)

pkgs/servers/ma1sd/default.nix

···
-{ lib, stdenv, fetchFromGitHub, jre, git, gradle, perl, makeWrapper }:
+{ lib, stdenv, fetchFromGitHub, jre, git, gradle_6, perl, makeWrapper }:
 
 let
   name = "ma1sd-${version}";
···
   deps = stdenv.mkDerivation {
     name = "${name}-deps";
     inherit src;
-    nativeBuildInputs = [ gradle perl git ];
+    nativeBuildInputs = [ gradle_6 perl git ];
 
     buildPhase = ''
       export MA1SD_BUILD_VERSION=${rev}
···
 in
 stdenv.mkDerivation {
   inherit name src version;
-  nativeBuildInputs = [ gradle perl makeWrapper ];
+  nativeBuildInputs = [ gradle_6 perl makeWrapper ];
   buildInputs = [ jre ];
 
   buildPhase = ''

pkgs/servers/mxisd/default.nix

···
-{ lib, stdenv, fetchFromGitHub, jre, git, gradle, perl, makeWrapper }:
+{ lib, stdenv, fetchFromGitHub, jre, git, gradle_6, perl, makeWrapper }:
 
 let
   name = "mxisd-${version}";
···
   deps = stdenv.mkDerivation {
     name = "${name}-deps";
     inherit src;
-    nativeBuildInputs = [ gradle perl git ];
+    nativeBuildInputs = [ gradle_6 perl git ];
 
     buildPhase = ''
       export MXISD_BUILD_VERSION=${rev}
···
 in
 stdenv.mkDerivation {
   inherit name src version;
-  nativeBuildInputs = [ gradle perl makeWrapper ];
+  nativeBuildInputs = [ gradle_6 perl makeWrapper ];
   buildInputs = [ jre ];
 
   patches = [ ./0001-gradle.patch ];