chore: bump org.codehaus.mojo:exec-maven-plugin from 3.6.3 to 3.6.4 (a2aproject#1154)

Bumps [org.codehaus.mojo:exec-maven-plugin](https://github.com/mojohaus/exec-maven-plugin) from 3.6.3 to 3.6.4.
- [Release notes](https://github.com/mojohaus/exec-maven-plugin/releases)
- [Commits](mojohaus/exec-maven-plugin@3.6.3...3.6.4)

---
updated-dependencies:
- dependency-name: org.codehaus.mojo:exec-maven-plugin
  dependency-version: 3.6.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

examples/helloworld/client/pom.xml

@@ -91,7 +91,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
-                <version>3.6.3</version>
+                <version>3.6.4</version>
                 <configuration>
                     <mainClass>org.a2aproject.sdk.examples.helloworld.client.HelloWorldClient</mainClass>
                     <systemProperties>

examples/stream-lifecycle/client/pom.xml

@@ -48,7 +48,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>
-                <version>3.6.3</version>
+                <version>3.6.4</version>
                 <configuration>
                     <mainClass>org.a2aproject.sdk.examples.streamlifecycle.client.StreamLifecycleClient</mainClass>
                 </configuration>