Make release validation portable

internal/config/config_test.go

@@ -1674,6 +1674,9 @@ func TestLoadSecretsRejectsInvalidDirectoryEntries(t *testing.T) {
 				t.Cleanup(func() {
 					_ = os.Chmod(path, 0o600)
 				})
+				if _, err := os.ReadFile(path); err == nil {
+					t.Skip("test process can read files without permission bits")
+				}
 			},
 			wantErr: "read secret file",
 		},