Remove weekly pre-commit autoupdate workflow

Deleted the `pre-commit-update.yml` workflow and its reference in the README. Reverted pre-commit hook versions to earlier stable releases due to compatibility or other considerations.

Author: MarkusB

.github/workflows/pre-commit-update.yml

@@ -19,10 +19,12 @@ repos:
     # Markdown linting
     # Config file: .markdownlint.yaml
   - repo: https://github.com/igorshubovych/markdownlint-cli
-    rev: v0.49.0
+    rev: v0.48.0
     hooks:
     - id: markdownlint
       args: [--fix]
+      language: node
+      language_version: '20.19.0'
 
   - repo: https://github.com/codespell-project/codespell
     rev: v2.4.2
@@ -31,7 +33,7 @@ repos:
 
     # Python linting and formatting
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.15.20
+    rev: v0.15.13
     hooks:
       - id: ruff
       - id: ruff-format
@@ -44,7 +46,7 @@ repos:
 
     # CMake linting and formatting
   - repo: https://github.com/BlankSpruce/gersemi-pre-commit
-    rev: 0.27.7
+    rev: 0.27.5
     hooks:
     - id: gersemi
       name: CMake linting

.pre-commit-config.yaml

@@ -100,7 +100,7 @@ Installed package version compatibility: `SameMajorVersion` (`mb_devenv_install_
 
 | Path | Role |
 | ------ | ------ |
-| `.github/workflows/` | `ci.yml` — Linux/macOS/Windows preset CI, Nix+Conan matrix, sanitizers, coverage, install test; `pre-commit-check.yml`; weekly `pre-commit-update.yml` |
+| `.github/workflows/` | `ci.yml` — Linux/macOS/Windows preset CI, Nix+Conan matrix, sanitizers, coverage, install test; `pre-commit-check.yml` |
 | `cmake/` | `dependencies.cmake` — `find_package` for build deps; mirror public deps in `mb.cpp-lib-template-config.cmake.in` with `find_dependency` (not test-only deps) |
 | `conan/profiles/` | Conan profiles for Nix+Conan CI |
 | `scripts/new-cpp-lib.py` | Template → new project ([above](#starting-a-new-library)) |