Update pytest-bdd to v8.0 (#1955)

* Encapsulate all multiline strings in triple-quotes in Gherkin files

Since pytest-bdd v8.0.0 uses the official Gherkin parser, multiline
strings must now be encapsulated by triple-quotes.

See:
- https://pytest-bdd.readthedocs.io/en/stable/#id2
- https://pytest-bdd.readthedocs.io/en/stable/#docstrings

* Remove comments in Gherkin files causing test breakage

These comments break the step matching.

* Fix compatibility of step-functions matching on multiple lines

In pytest-bdd v8.0.0 it is no longer possible to match based on multiple
lines, which breaks essentially all steps that support docstrings. Solve
this by adding a wrapper-function for each of these instances, that
matches the docstring step, and calls the original function.

So, what used to be:

    @then(parse("the output should match\n{regex}"))
    @then(parse('the output should match "{regex}"'))
    def output_should_match(regex, cli_run):
        ...

Is now:

    @then(parse("the output should match"))
    def output_should_match_docstring(cli_run, docstring):
        output_should_match(docstring, cli_run)

    @then(parse('the output should match "{regex}"'))
    def output_should_match(regex, cli_run):
        ...

There is possibly a way around this that is much better than what I've
done here, but this is a start at least.

* Update version requirement of pytest-bdd to >=8.0

* Update tox config to match poetry config

---------

Co-authored-by: Micah Jerome Ellison <micah.jerome.ellison@gmail.com>

tests/bdd/features/template.feature

@@ -2,12 +2,13 @@
 # License: https://www.gnu.org/licenses/gpl-3.0.html
 
 Feature: Using templates
-
     Scenario Outline: Template contents should be used in new entry
         Given we use the config "<config_file>"
         And we use the password "test" if prompted
         And we append to the editor if opened
+            """
             This is an addition to a templated entry
+            """
         When we run "jrnl --config-override template features/templates/basic.template"
         And we run "jrnl -1"
         Then the output should contain "This text is in the basic template"