Two small improvements

1. Change requirements.txt to allow either zstandard 0.20 or 0.21. That
   prevents a downgrade for people who already have 0.21 installed, while
   also allowing CI to find 0.20.
2. Move compressformat parameter earlier in compress_files() function.
   It made a bit more sense to have it earlier; as long as consumers are
   correctly using positional kwargs, it shouldn't break anyone.

conans/client/cmd/uploader.py

@@ -263,7 +263,7 @@ def upload_package(self, pref, prev_bundle, remote):
         self._output.debug(f"Upload {pref} in {duration} time")
 
 
-def compress_files(files, name, dest_dir, compresslevel=None, ref=None, compressformat=None):
+def compress_files(files, name, dest_dir, compressformat=None, compresslevel=None, ref=None):
     t1 = time.time()
     tar_path = os.path.join(dest_dir, name)
     if name in (PACKAGE_TGZ_NAME, PACKAGE_TZSTD_NAME, EXPORT_SOURCES_TGZ_NAME) and len(files) > 100:

conans/requirements.txt

@@ -7,4 +7,4 @@ fasteners>=0.15
 distro>=1.4.0, <=1.8.0; sys_platform == 'linux' or sys_platform == 'linux2'
 Jinja2>=3.0, <4.0.0
 python-dateutil>=2.8.0, <3
-zstandard==0.20.0
+zstandard>=0.20, <= 0.21