Bump Go to 1.25-rc.1

Author: mbg

.github/workflows/__all-platform-bundle.yml

@@ -117,7 +117,7 @@ def writeHeader(checkStream):
             'name': 'Install Go',
             'uses': 'actions/setup-go@v5',
             'with': {
-                'go-version': '>=1.21.0',
+                'go-version': '1.25-rc.1',
                 # to avoid potentially misleading autobuilder results where we expect it to download
                 # dependencies successfully, but they actually come from a warm cache
                 'cache': False