Use alpine:3.13, not latest

Author: pugnascotia

distribution/docker/build.gradle

@@ -305,7 +305,7 @@ void addBuildDockerImageTask(Architecture architecture, DockerBase base) {
         baseImages = [baseImage]
         buildArgs = buildArgsMap
       } else if (base == DockerBase.CENTOS) {
-        baseImages = ['alpine:latest', base.image]
+        baseImages = ['alpine:3.13', base.image]
       } else {
         baseImages = [base.image]
       }

qa/os/src/test/java/org/elasticsearch/packaging/util/Docker.java

@@ -299,7 +299,7 @@ private static void executePrivilegeEscalatedShellCmd(String shellCmd, Path loca
         args.add("--volume \"" + localPath.getParent() + ":" + containerPath.getParent() + "\"");
 
         // Use a lightweight musl libc based small image
-        args.add("alpine");
+        args.add("alpine:3.13");
 
         // And run inline commands via the POSIX shell
         args.add("/bin/sh -c \"" + shellCmd + "\"");