ci: Also build wheel in build stage

3 jobs for master in 37 seconds (queued for 2 seconds)
Name Stage Failure
build-linux Build
  File "/builds/gajim/python-nbxmpp/.ci/", line 58, in prepare_package_dir
tarball = Path(shutil.copy(context.tarball, BUILD_DIR))
File "/usr/lib/python3.9/", line 418, in copy
copyfile(src, dst, follow_symlinks=follow_symlinks)
File "/usr/lib/python3.9/", line 264, in copyfile
with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
FileNotFoundError: [Errno 2] No such file or directory: 'dist/nbxmpp-3.1.1-py3-none-any.whl\ndist/nbxmpp-3.1.1.tar.gz'
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1