Modernize tox-poetry integration

I have never been a fan of poetry, but since this project is already
using it, let's keep it this way. What we have to do though is to make
sure we use the up-to-date poetry configuration and best practices.

This patch moves dependency definitions out from tox.ini to
pyproject.toml (poetry groups). This should help us to maintain
dependencies in one place only.

.github/workflows/ci.yml

@@ -49,4 +49,4 @@ jobs:
         if: matrix.os == 'macos-latest'
 
       - name: Run pytest
-        run: pipx run tox -e py3
+        run: pipx run tox -e test

pyproject.toml

@@ -1,3 +1,7 @@
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"
+
 [tool.poetry]
 name = "httpie-credential-store"
 version = "3.1.0"
@@ -14,18 +18,23 @@ python = "^3.8"
 httpie = "^3.1"
 keyring = ">= 23.5"
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.lint]
+optional = true
+
+[tool.poetry.group.lint.dependencies]
+ruff = "^0.4.2"
+
+[tool.poetry.group.test]
+optional = true
+
+[tool.poetry.group.test.dependencies]
 pytest = "^7.1"
 responses = "^0.20"
 
 [tool.poetry.plugins."httpie.plugins.auth.v1"]
 credential-store = "httpie_credential_store:CredentialStoreAuthPlugin"
 creds = "httpie_credential_store:CredsAuthPlugin"
 
-[build-system]
-requires = ["poetry>=0.12"]
-build-backend = "poetry.masonry.api"
-
 [tool.ruff]
 line-length = 100
 target-version = "py38"

tox.ini

@@ -1,17 +1,16 @@
 [tox]
-envlist = py3, lint
+envlist = lint, test
 
 [testenv]
-deps = poetry
+allowlist_externals = poetry
 skip_install = true
-commands =
-    poetry install -v
-    poetry run pytest -vv
+
+[testenv:test]
+commands_pre = poetry install --with test
+commands = poetry run pytest -vv {posargs:.}
 
 [testenv:lint]
-skip_install = true
-deps =
-    ruff >= 0.4.2, < 0.5.0
+commands_pre = poetry install --only lint
 commands =
-    ruff check {args:.}
-    ruff format --check --diff {args:.}
+    ruff check {posargs:.}
+    ruff format --check --diff {posargs:.}