Fix test_wps_parser and test_wps_resolve_rules

[eyvorchuk]

Upon running the make installation or running pytest, test_wps_parser and test_wps_resolve_rules will fail and should be fixed when possible. However, the associated notebook demos work properly. The first test yields the following error:

________________________ test_wps_parser[conditions0] _________________________

conditions = ['(temp_djf_iamean_s100p_hist < 5)', '(temp_djf_iamean_s0p_hist < -6)', '(temp_djf_iamean_s0p_hist < -6) && (temp_djf_iamean_s100p_hist > -6)']

    @pytest.mark.parametrize(
        ("conditions"),
        [
            [
                "(temp_djf_iamean_s100p_hist < 5)",
                "(temp_djf_iamean_s0p_hist < -6)",
                "(temp_djf_iamean_s0p_hist < -6) && (temp_djf_iamean_s100p_hist > -6)",
            ]
        ],
    )
    def test_wps_parser(conditions):
        datainput = build_condition_input(conditions)
>       run_wps_process(Parser(), datainput)

tests/test_wps_parser.py:30: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/tmp/sandpiper-venv/lib/python3.8/site-packages/wps_tools/testing.py:104: in run_wps_process
    resp = client.get(
/tmp/sandpiper-venv/lib/python3.8/site-packages/wps_tools/testing.py:33: in get
    return super(WpsTestClient, self).get(query)
/tmp/sandpiper-venv/lib/python3.8/site-packages/werkzeug/test.py:1129: in get
    return self.open(*args, **kw)
/tmp/sandpiper-venv/lib/python3.8/site-packages/werkzeug/test.py:1075: in open
    response = self.response_wrapper(*response, request=request)
/tmp/sandpiper-venv/lib/python3.8/site-packages/werkzeug/test.py:1297: in __init__
    super().__init__(response, status, headers, **kwargs)
/tmp/sandpiper-venv/lib/python3.8/site-packages/pywps/tests.py:118: in __init__
    self.xml = etree.fromstring(self.get_data())
/tmp/sandpiper-venv/lib/python3.8/site-packages/pywps/xml_util.py:12: in fromstring
    return _etree.fromstring(text, parser=PARSER)
src/lxml/etree.pyx:3237: in lxml.etree.fromstring
    ???
src/lxml/parser.pxi:1896: in lxml.etree._parseMemoryDocument
    ???
src/lxml/parser.pxi:1784: in lxml.etree._parseDoc
    ???
src/lxml/parser.pxi:1141: in lxml.etree._BaseParser._parseDoc
    ???
src/lxml/parser.pxi:615: in lxml.etree._ParserContext._handleParseResultDoc
    ???
src/lxml/parser.pxi:725: in lxml.etree._handleParseResult
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

>   ???
E     File "<string>", line 17
E   lxml.etree.XMLSyntaxError: StartTag: invalid element name, line 17, column 119

src/lxml/parser.pxi:654: XMLSyntaxError

And each test_wps_resolve_rules test yields the following error:

Traceback (most recent call last):
  File "/tmp/sandpiper-venv/lib/python3.8/site-packages/pywps/app/Process.py", line 250, in _run_process
    self.handler(wps_request, wps_response)  # the user must update the wps_response.
  File "/home/eyvorchuk/Documents/sandpiper/sandpiper/processes/wps_resolve_rules.py", line 122, in _handler
    connection_string = update_connection(connection_string)
  File "/home/eyvorchuk/Documents/sandpiper/sandpiper/utils.py", line 31, in update_connection
    raise ProcessError(
pywps.app.exceptions.ProcessError: No connection_string found. You must set the connection_string through the environment or as a parameter.