Use 'buildkit' as default scope (#516)

This PR updates the schema to use the correct default value for `scope`
in the GHA caching options. This should be effectively a no-op.


From: https://docs.docker.com/build/cache/backends/gha/

<img width="892" alt="image"
src="https://github.com/user-attachments/assets/690cde79-e30e-4085-81fd-1c9dc1c6d7e9"
/>


Closes #496

sdk/python/pulumi_docker_build/_inputs.py

@@ -332,7 +332,7 @@ class CacheFromGitHubActionsArgs:
                environment variable to your jobs.
         """
         if scope is None:
-            scope = (_utilities.get_env('buildkit') or '')
+            scope = 'buildkit'
         if scope is not None:
             pulumi.set(__self__, "scope", scope)
         if token is None:
@@ -1048,7 +1048,7 @@ class CacheToGitHubActionsArgs:
         if mode is not None:
             pulumi.set(__self__, "mode", mode)
         if scope is None:
-            scope = (_utilities.get_env('buildkit') or '')
+            scope = 'buildkit'
         if scope is not None:
             pulumi.set(__self__, "scope", scope)
         if token is None:

sdk/python/pulumi_docker_build/outputs.py

@@ -315,7 +315,7 @@ class CacheFromGitHubActions(dict):
                environment variable to your jobs.
         """
         if scope is None:
-            scope = (_utilities.get_env('buildkit') or '')
+            scope = 'buildkit'
         if scope is not None:
             pulumi.set(__self__, "scope", scope)
         if token is None:
@@ -835,7 +835,7 @@ class CacheToGitHubActions(dict):
         if mode is not None:
             pulumi.set(__self__, "mode", mode)
         if scope is None:
-            scope = (_utilities.get_env('buildkit') or '')
+            scope = 'buildkit'
         if scope is not None:
             pulumi.set(__self__, "scope", scope)
         if token is None: