Add the other special envvar

Author: mdboom

.github/workflows/build-wheel.yml

@@ -41,6 +41,7 @@ jobs:
                  (inputs.host-platform == 'linux-aarch64' && 'linux-arm64-cpu8') ||
                  (inputs.host-platform == 'win-64' && 'windows-2022') }}
     env:
+      SCCACHE_GHA_ENABLED: "true"
       CC: "sccache cc"
       CXX: "sccache c++"