convert uses of interface{} to any

Done via:
  find . -name "*.go" | xargs sed -i -E 's/interface\{\}/any/g'

PiperOrigin-RevId: 487033228

tools/go_generics/go_merge/main.go

@@ -33,7 +33,7 @@ var (
 	output = flag.String("o", "", "output `file`")
 )
 
-func fatalf(s string, args ...interface{}) {
+func fatalf(s string, args ...any) {
 	fmt.Fprintf(os.Stderr, s, args...)
 	os.Exit(1)
 }

tools/go_generics/tests/all_stmts/input.go

@@ -237,7 +237,7 @@ R:
 
 	// Type switch statements.
 	{
-		var interfaceFunc func(T) interface{}
+		var interfaceFunc func(T) any
 
 		switch interfaceFunc(T(0)).(type) {
 		case *T, T, int:

tools/go_generics/tests/all_stmts/output.go

@@ -235,7 +235,7 @@ R:
 
 	// Type switch statements.
 	{
-		var interfaceFunc func(Q) interface{}
+		var interfaceFunc func(Q) any
 
 		switch interfaceFunc(Q(0)).(type) {
 		case *Q, Q, int: