[DATALAD RUNCMD] Use python 3.8 env to overcome some odd ssl issues on ubuntu

since we are to test git-annex here I think it is totally ok to not demand the lowest supported by datalad version of python.

ATM we are getting errors like

self = <ssl.SSLSocket [closed] fd=94, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6>
len = 8192
buffer = bytearray(b'\xf0\x13`I\xe4\x7f\x00\x00\xf0\x13`I\xe4\x7f\x00\x00\xd0\x02\x91a|U\x00\x00\xd0\x02\x91a|U\x00\x00nently\r...0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')

    def read(self, len=1024, buffer=None):
        """Read up to LEN bytes and return them.
        Return zero-length string on EOF."""

        self._checkClosed()
        if self._sslobj is None:
            raise ValueError("Read on closed or unwrapped SSL socket.")
        try:
            if buffer is not None:
>               return self._sslobj.read(len, buffer)
E               ssl.SSLError: [SSL: KRB5_S_TKT_NYV] unexpected eof while reading (_ssl.c:2570)

/opt/hostedtoolcache/Python/3.7.15/x64/lib/python3.7/ssl.py:929: SSLError
=============================== warnings summary ===============================
distributed/tests/test_ria_basics.py::test_initremote_basic_httpsurl
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None-test1.txt]
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None-test_fpath1]
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None-test_fpath2]
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None-file with space test4]
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None-\u0414\u0436\u044d\u0439\u0441\u043e\u043d]
tests/test_tests_utils_pytest.py::test_serve_path_via_http[True-None- |;&%b5{}'"<>\u0394\u0419\u05e7\u0645\u0e57\u3042 .datc ]

and I have vague memory it is 3.7 specific

=== Do not change lines below === { "chain": [], "cmd": "git-sedi '3\.7' '3\.8'", "exit": 0, "extra_inputs": [], "inputs": [], "outputs": [], "pwd": "." } ^^^ Do not change lines above ^^^

datalad / git-annex

[DATALAD RUNCMD] Use python 3.8 env to overcome some odd ssl issues on ubuntu #148