Revert "Bump CEL to 0.11.2"

This reverts commit 4c90653d19.

vendor/github.com/google/cel-go/interpreter/activation.go

@@ -35,17 +35,13 @@ type Activation interface {
 	Parent() Activation
 }
 
-// EmptyActivation returns a variable-free activation.
+// EmptyActivation returns a variable free activation.
 func EmptyActivation() Activation {
-	return emptyActivation{}
+	// This call cannot fail.
+	a, _ := NewActivation(map[string]interface{}{})
+	return a
 }
 
-// emptyActivation is a variable-free activation.
-type emptyActivation struct{}
-
-func (emptyActivation) ResolveName(string) (interface{}, bool) { return nil, false }
-func (emptyActivation) Parent() Activation                     { return nil }
-
 // NewActivation returns an activation based on a map-based binding where the map keys are
 // expected to be qualified names used with ResolveName calls.
 //