Using single quote style when setting annotations

Annotations must be strings.  Use single-quote style
so tools don't get confused about the type.

kyaml/yaml/fns_test.go

@@ -637,12 +637,12 @@ func TestSetAnnotation_Fn(t *testing.T) {
 kind: Deployment`))
 
 	rn := assertNoError(t)(r0.Pipe(SetAnnotation("a.b.c", "d.e.f")))
-	assert.Equal(t, "d.e.f\n", assertNoErrorString(t)(rn.String()))
+	assert.Equal(t, "'d.e.f'\n", assertNoErrorString(t)(rn.String()))
 	assert.Equal(t, `apiVersion: apps/v1
 kind: Deployment
 metadata:
   annotations:
-    a.b.c: d.e.f
+    a.b.c: 'd.e.f'
 `, assertNoErrorString(t)(r0.String()))
 }