build: pin mkdocs<2 to stay clear of the MkDocs 2.0 rewrite (#21)

MkDocs 2.0 is a backward-incompatible rewrite (no plugin system, no theme
overrides, no migration path) that breaks Material for MkDocs. Material 9.7.5+
already caps mkdocs<2; make that explicit and bump the Material floor so a fresh
resolve can never pull MkDocs 2.0. Docs continue to build on mkdocs 1.6.1 /
mkdocs-material 9.7.6.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lesnik512

pyproject.toml

@@ -4,7 +4,13 @@ version = "0"
 description = "modern-python.org organization homepage"
 requires-python = ">=3.11"
 dependencies = [
-    "mkdocs-material>=9.5",
+    # MkDocs 2.0 is a backward-incompatible rewrite (no plugin system, no theme
+    # overrides) that breaks Material for MkDocs, with no migration path. Material
+    # 9.7.5+ already caps mkdocs<2; pin both explicitly so a fresh resolve can
+    # never pull MkDocs 2.0.
+    # https://squidfunk.github.io/mkdocs-material/blog/2026/02/18/mkdocs-2.0/
+    "mkdocs>=1.6,<2",
+    "mkdocs-material>=9.7.5",
 ]
 
 [dependency-groups]