[FIX] runbot: remove useless pip warning

When pip installs a package that contains a script, it goes in
`~/.local/bin` directory of the current user. This leads to a log warning
to warn the user that the script won't be accessible by other users.

e.g.:
`WARNING: The script pygmentize is installed in '/home/odoo/.local/bin'
which is not on PATH.`

This is particularly annoying for documentation builds because it may
confuse the users.

runbot/models/build.py

@@ -993,7 +993,7 @@ def _cmd(self, python_params=None, py_version=None, local_only=True, sub_command
             if not self.params_id.skip_requirements and os.path.isfile(commit_id._source_path('requirements.txt')):
                 repo_dir = self._docker_source_folder(commit_id)
                 requirement_path = os.path.join(repo_dir, 'requirements.txt')
-                pres.append([f'python{py_version}', '-m', 'pip', 'install','--user', '--progress-bar', 'off', '-r', f'{requirement_path}'])
+                pres.append([f'python{py_version}', '-m', 'pip', 'install','--user', '--progress-bar', 'off', '--no-warn-script-location', '-r', f'{requirement_path}'])
 
         addons_paths = self._get_addons_path()
         (server_commit, server_file) = self._get_server_info()