Update copyright date to 2019

BenWhitehead · BenWhitehead · commit f7470f3a8832 · 2019-08-16T11:32:09.000-04:00
diff --git a/firestore/src/update_doc_increment.php b/firestore/src/update_doc_increment.php
@@ -1,6 +1,6 @@
 <?php
 /**
- * Copyright 2018 Google LLC.
+ * Copyright 2019 Google LLC.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`
`2`	`2`	`/**`
`3`		`- * Copyright 2018 Google LLC.`
	`3`	`+ * Copyright 2019 Google LLC.`
`4`	`4`	`*`
`5`	`5`	`* Licensed under the Apache License, Version 2.0 (the "License");`
`6`	`6`	`* you may not use this file except in compliance with the License.`