astro/mepo: unbreak fetch due to recompression

> Fetched file size mismatch (expected 591041, actual 590350)

$ gzip -l mepo-1.1.2.tar.gz

compressed uncompressed  ratio uncompressed_name

• 591041 1024000 42.2% mepo-1.1.2.tar

+ 590350 1024000 42.3% mepo-1.1.2.tar