build: move toxfile to tools packages

tools/tox_plugins/pyproject.toml

@@ -0,0 +1,18 @@
+[build-system]
+requires = [
+    "hatchling",
+]
+build-backend = "hatchling.build"
+
+[project]
+name = "ahriman-tox-plugins"
+classifiers = [
+    "Framework :: tox",
+]
+version = "1"
+
+[project.entry-points.tox]
+dynamic-version = "dynamic_version"
+
+[tool.hatch.build.targets.wheel]
+packages = ["dynamic_version"]