traefik plugin 0.7.7 (#73)

* Automatic discovery of the scopes.

Issue #61 raised very valid concerns about users configuring scopes that are not supported by the provider.
This change introduces automatic discovery of supported scopes by fetching the provider's discovery document and filtering out unsupported scopes.

Before:
User configures: scopes: ["openid", "profile", "email", "offline_access"]
Self-hosted GitLab: "The requested scope is invalid, unknown, or malformed"
Authentication: ❌ FAILS

After:
User configures: scopes: ["openid", "profile", "email", "offline_access"]
Middleware checks discovery doc → offline_access not supported
Automatically filters to: ["openid", "profile", "email"]
Authentication: ✅ SUCCEEDS

* Resolves issue #74 by enabling user to specify expected audience in the configuration.

* Fix flaky tests.

singleton_resources_test.go

@@ -276,6 +276,7 @@ func TestContextAwareGoroutineManagement(t *testing.T) {
 
 	t.Run("SingletonTasksAcrossInstances", func(t *testing.T) {
 		// Reset singletons to ensure clean state
+		ResetGlobalTaskRegistry() // Reset circuit breaker and task registry
 		resetResourceManagerForTesting()
 		ResetUniversalCacheManagerForTesting()
 		defer ResetUniversalCacheManagerForTesting()
@@ -312,13 +313,35 @@ func TestContextAwareGoroutineManagement(t *testing.T) {
 			plugins = append(plugins, plugin)
 		}
 
-		// Wait for cleanup to run multiple times
-		time.Sleep(350 * time.Millisecond)
+		// Wait for cleanup to run at least 2 times with adaptive timeout
+		// This handles race detector overhead which can slow goroutine scheduling significantly
+		// When running as part of full test suite, CPU contention is even higher, so use generous timeout
+		const minExpectedCount = 2
+		const maxExpectedCount = 5
+		timeout := time.After(5 * time.Second)
+		ticker := time.NewTicker(50 * time.Millisecond)
+		defer ticker.Stop()
 
-		// Check that cleanup ran but not excessively (should be singleton)
-		count := atomic.LoadInt32(&cleanupCount)
-		if count < 2 || count > 5 {
-			t.Errorf("Unexpected cleanup count: %d (expected 2-5 for singleton)", count)
+		var count int32
+	waitLoop:
+		for {
+			select {
+			case <-ticker.C:
+				count = atomic.LoadInt32(&cleanupCount)
+				if count >= minExpectedCount {
+					// Success: reached minimum threshold
+					break waitLoop
+				}
+			case <-timeout:
+				count = atomic.LoadInt32(&cleanupCount)
+				t.Errorf("Timeout waiting for cleanup count to reach %d, got %d (race detector may be slowing execution)", minExpectedCount, count)
+				break waitLoop
+			}
+		}
+
+		// Verify count is within expected range (should be singleton, not running excessively)
+		if count > maxExpectedCount {
+			t.Errorf("Cleanup count too high: %d (expected max %d for singleton)", count, maxExpectedCount)
 		}
 
 		// Cleanup