chore(main): release 2.56.3 (#3775)

🤖 I have created a release *beep* *boop*
---


<details><summary>2.56.3</summary>

##
[2.56.3](v2.56.2...v2.56.3)
(2025-05-02)


### Bug Fixes

* Only send mtlsEndpoint if it is non-null
([#3767](#3767))
([8f8df7b](8f8df7b))
* subscribe Airlock Docker image definition to GRPC updates
([#3765](#3765))
([d0f43e3](d0f43e3))


### Dependencies

* update dependency com.google.errorprone:error_prone_annotations to
v2.38.0
([#3773](#3773))
([e16fe65](e16fe65))
* update gapic-showcase to 36.2
([#3771](#3771))
([15b2577](15b2577))
* update google auth library dependencies to v1.34.0
([#3772](#3772))
([406a180](406a180))
* Update maven-shared-utils to v3.2.1
([#3768](#3768))
([7ec93c3](7ec93c3))
</details>

---
This PR was generated with [Release
Please](https://github.com/googleapis/release-please). See
[documentation](https://github.com/googleapis/release-please#release-please).

---------

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: Lawrence Qiu <[email protected]>

Author: release-please[bot]

java-iam/pom.xml

@@ -145,12 +145,12 @@
       <dependency>
         <groupId>com.google.api.grpc.api.grpc</groupId>
         <artifactId>proto-google-iam-v3</artifactId>
-        <version>1.50.3-SNAPSHOT</version><!-- {x-version-update:proto-google-iam-v3:current} -->
+        <version>1.50.3</version><!-- {x-version-update:proto-google-iam-v3:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc.api.grpc</groupId>
         <artifactId>grpc-google-iam-v3</artifactId>
-        <version>1.50.3-SNAPSHOT</version><!-- {x-version-update:grpc-google-iam-v3:current} -->
+        <version>1.50.3</version><!-- {x-version-update:grpc-google-iam-v3:current} -->
       </dependency>
       <dependency>
         <groupId>javax.annotation</groupId>