Changes

osmo_git_clone_url(): add Gitea mirrors for libnftnl and nftables

Change-Id: I830a16c8bf7f595b16113bf2ba5e81bae56533dd
Related: osmo-upf.git I28950d823dfd91e8e2ac23a19e5a86d1027096b3

scripts: fix deprecation warnings

scripts/verify_value_string_arrays_are_terminated.py:22: SyntaxWarning:
    "\s" is an invalid escape sequence. Such sequences will not work in the future.
    Did you mean "\\s"? A raw string is also an option.
scripts/verify_value_string_arrays_are_terminated.py:22: SyntaxWarning:
    "\s" is an invalid escape sequence. Such sequences will not work in the future.
    Did you mean "\\s"? A raw string is also an option.
scripts/verify_value_string_arrays_are_terminated.py:23: SyntaxWarning:
    "\s" is an invalid escape sequence. Such sequences will not work in the future.
    Did you mean "\\s"? A raw string is also an option.
scripts/verify_value_string_arrays_are_terminated.py:23: SyntaxWarning:
    "\s" is an invalid escape sequence. Such sequences will not work in the future.
    Did you mean "\\s"? A raw string is also an option.
scripts/verify_value_string_arrays_are_terminated.py:30: DeprecationWarning:
    codecs.open() is deprecated. Use open() instead.

Change-Id: Ie78b84dd556266f96780a4232f95b58e0e3eabc0