build: optimize compression method and clean up environment variables (#552)

- Replace tar command with xz command for compression
- Remove redundant environment variable XZ_OPT

ref: https://gitea.com/gitea/homebrew-gitea/pulls/164

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

Reviewed-on: https://gitea.com/gitea/tea/pulls/552
Reviewed-by: techknowlogick <techknowlogick@noreply.gitea.io>
Co-authored-by: appleboy <appleboy.tw@gmail.com>
Co-committed-by: appleboy <appleboy.tw@gmail.com>

.goreleaser.yaml

@@ -71,10 +71,8 @@ builds:
   no_unique_dist_dir: true
   hooks:
     post:
-      - cmd: tar -cJf {{ .Path }}.xz {{ .Path }}
+      - cmd: xz -k -9 {{ .Path }}
         dir: ./dist/
-        env:
-          - XZ_OPT=-9
       - cmd: sh .goreleaser.checksum.sh {{ .Path }}
       - cmd: sh .goreleaser.checksum.sh {{ .Path }}.xz