Build arm64v8 images for openjdk-8

I think these didn't used to be available upstream, but they are now listed in https://github.com/docker-library/official-images/blob/master/library/openjdk

library/clojure

@@ -8,27 +8,21 @@ Tags: latest
 Directory: target/openjdk-11-slim-bullseye/latest
 
 Tags: openjdk-8-buster, openjdk-8-lein-buster, openjdk-8-lein-2.9.6-buster
-Architectures: amd64
 Directory: target/openjdk-8-buster/lein
 
 Tags: openjdk-8-slim-buster, openjdk-8-lein-slim-buster, openjdk-8-lein-2.9.6-slim-buster
-Architectures: amd64
 Directory: target/openjdk-8-slim-buster/lein
 
 Tags: openjdk-8-boot-buster, openjdk-8-boot-2.8.3-buster
-Architectures: amd64
 Directory: target/openjdk-8-buster/boot
 
 Tags: openjdk-8-boot-slim-buster, openjdk-8-boot-2.8.3-slim-buster
-Architectures: amd64
 Directory: target/openjdk-8-slim-buster/boot
 
 Tags: openjdk-8-tools-deps-buster, openjdk-8-tools-deps-1.10.3.967-buster
-Architectures: amd64
 Directory: target/openjdk-8-buster/tools-deps
 
 Tags: openjdk-8-tools-deps-slim-buster, openjdk-8-tools-deps-1.10.3.967-slim-buster
-Architectures: amd64
 Directory: target/openjdk-8-slim-buster/tools-deps
 
 Tags: openjdk-11-buster, openjdk-11-lein-buster, openjdk-11-lein-2.9.6-buster, lein-buster, lein-2.9.6-buster