chore: bump sam/build-java21 (#2075)

Bumps sam/build-java21 from `44e9166` to `6ad1664`.

---
updated-dependencies:
- dependency-name: sam/build-java21
  dependency-version: 6ad16645a48cbc9aa6ab9b707350d1976804f410bb47dd0f87bf106cd69ff36a
  dependency-type: direct:production
...

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

Author: dependabot[bot]

powertools-e2e-tests/src/test/resources/docker/Dockerfile

@@ -1,5 +1,5 @@
 # Use the official AWS SAM base image for Java 21
-FROM public.ecr.aws/sam/build-java21@sha256:44e9166767b12df862da6f76b4622f89e3b97a31bab73bfbb3b1df13515bfd23
+FROM public.ecr.aws/sam/build-java21@sha256:6ad16645a48cbc9aa6ab9b707350d1976804f410bb47dd0f87bf106cd69ff36a
 
 # Install GraalVM dependencies
 RUN curl -4 -L https://download.oracle.com/graalvm/21/latest/graalvm-jdk-21_linux-x64_bin.tar.gz | tar -xvz