chore(main): release 2.18.1 (#2639)

Author: release-please[bot]

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [2.18.1](https://github.com/googleapis/google-api-php-client/compare/v2.18.0...v2.18.1) (2024-11-24)
+
+
+### Bug Fixes
+
+* Implicitly marking parameter  as nullable is deprecated ([#2638](https://github.com/googleapis/google-api-php-client/issues/2638)) ([de57db2](https://github.com/googleapis/google-api-php-client/commit/de57db2fdc0d56de1abbf778b28b77c3347eb3fd))
+
 ## [2.18.0](https://github.com/googleapis/google-api-php-client/compare/v2.17.0...v2.18.0) (2024-10-16)