feat: improve API usage and test coverage across platforms

- Add an option to include extra pre-existing files in the release with a specified file format (`.xz`)

Signed-off-by: appleboy <appleboy.tw@gmail.com>

.goreleaser.yaml

@@ -82,3 +82,12 @@ checksum:
 
 snapshot:
   name_template: "{{ incpatch .Version }}"
+
+release:
+  # You can add extra pre-existing files to the release.
+  # The filename on the release will be the last part of the path (base).
+  # If another file with the same name exists, the last one found will be used.
+  #
+  # Templates: allowed
+  extra_files:
+    - glob: ./**.xz