chore: Cleanup images and use hash for exports tag (#158)

I noticed that making changes to the exports script before a release
could cause modules to not build properly if breaking changes got pushed
out. To prevent this, I'm making it so that the hash of the commit is
put in the tag for the exports script image and that the CLI tool will
use that hash when building the `Containerfile`.

template/src/lib.rs

@@ -27,6 +27,9 @@ pub struct ContainerFileTemplate<'a> {
 
     #[builder(setter(into))]
     registry: Cow<'a, str>,
+
+    #[builder(setter(into))]
+    exports_tag: Cow<'a, str>,
 }
 
 #[derive(Debug, Clone, Template, TypedBuilder)]