Update pyproject.toml for new dependency group handling for poetry

Dependency groups are now a thing, and the old `dev-dependencies`
section will soon be deprecated according to the poetry docs. So, this
updates pyproject.toml to use the new format.

Please note that poetry v1.2+ is now required for this project, but
there's currently no way to specify or enforce that in poetry, so the
contributing docs have been updated to get that point across.

see: https://python-poetry.org/docs/master/managing-dependencies/#dependency-groups
see: python-poetry/poetry#3316

Author: wren

docs/contributing.md

@@ -70,7 +70,7 @@ When discussing new features, please keep in mind our design goals. jrnl strives
 
 ### Getting your environment set up
 
-You will need to install [poetry](https://python-poetry.org/) to develop jrnl. It will take care of all of the project's other dependencies.
+You will need to install [poetry v1.2+](https://python-poetry.org/) to develop jrnl. It will take care of all of the project's other dependencies.
 
 ### Understanding the branches
 
@@ -88,7 +88,7 @@ You can find an inventory of commands in the `pyproject.toml`. Users can run the
 A typical development workflow includes:
 
  * Installing dependencies:
-    * `poetry install`
+    * `poetry install` (or `poetry install --with docs` for optional dependencies)
  * Activate virtual environment:
     * `poetry shell`
  * Running the source in a virtual environment:

pyproject.toml

@@ -42,23 +42,31 @@ rich = "^12.2.0"
 # dayone-only deps
 tzlocal = ">=4.0"   # https://github.com/regebro/tzlocal/blob/master/CHANGES.txt
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.dev.dependencies]
+ipdb = "*"
+poethepoet = "*"
+
+[tool.poetry.group.lint.dependencies]
 black = { version = ">=21.5b2", allow-prereleases = true }
 flakeheaven = ">=3.0"
 flake8-black = ">=0.3.3"
 flake8-isort = ">=5.0.0"
 flake8-type-checking = ">=2.2.0"
-ipdb = "*"
 isort = ">=5.10"
-mkdocs = ">=1.0,<1.3"
-poethepoet = "*"
+
+[tool.poetry.group.test.dependencies]
+tox = "*"
 pytest = ">=6.2"
 pytest-bdd = ">=4.0.1,<6.0"
-pytest-clarity = "*"
 pytest-xdist = ">=2.5.0"
-requests = "*"
 toml = ">=0.10"
-tox = "*"
+
+[tool.poetry.group.docs]
+optional = true
+[tool.poetry.group.docs.dependencies]
+# For docs: don't forget to run `npm install`
+mkdocs = ">=1.0,<1.3"
+requests = "*"
 xmltodict = "*"
 
 [tool.poetry.scripts]