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/file_storage.feature

@@ -8,7 +8,9 @@ Feature: Journals iteracting with the file system in a way that users can see
         When we run "jrnl 23 July 2013: Testing folder journal."
         Then we should get no error
         And the journal directory should contain
+            """
             2013/07/23.txt
+            """
 
     Scenario: Adding multiple entries to a Folder journal should generate multiple date files
         Given we use the config "empty_folder.yaml"
@@ -16,7 +18,9 @@ Feature: Journals iteracting with the file system in a way that users can see
         And we run "jrnl 3/7/2014: Second entry of journal."
         Then we should get no error
         And the journal directory should contain
+            """
             2013/07/23.txt
+            """
 
     Scenario: If the journal and its parent directory don't exist, they should be created
         Given we use the config "missing_directory.yaml"
@@ -33,7 +37,7 @@ Feature: Journals iteracting with the file system in a way that users can see
         Then the journal should exist
         When we run "jrnl -99 --short"
         Then the output should contain "This is a new entry in my journal"
-    
+
     @on_posix
     Scenario: If the directory for a Folder journal ending in a slash ('/') doesn't exist, then it should be created
         Given we use the config "missing_directory.yaml"
@@ -55,9 +59,11 @@ Feature: Journals iteracting with the file system in a way that users can see
     Scenario: Creating journal with relative path should update to absolute path
         Given we use no config
         When we run "jrnl hello world" and enter
+            """
             test.txt
             n
             \n
+            """
         Then the output should contain "Journal 'default' created"
         When we change directory to "subfolder"
         And we run "jrnl -n 1"