Bump com.android.tools:r8 from 8.0.40 to 8.1.56 (#2462)

Bumps com.android.tools:r8 from 8.0.40 to 8.1.56.

---
updated-dependencies:
- dependency-name: com.android.tools:r8
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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shrinker-test/pom.xml

@@ -203,7 +203,7 @@
               but it appears that can be ignored -->
             <groupId>com.android.tools</groupId>
             <artifactId>r8</artifactId>
-            <version>8.0.40</version>
+            <version>8.1.56</version>
           </dependency>
         </dependencies>
       </plugin>