Use pre-commit to prevent adding .rej files and ongoing merge conflicts

.pre-commit-config.yaml

@@ -1,4 +1,12 @@
 repos:
+  - repo: local
+    hooks:
+      # Prevent committing .rej files
+      - id: forbidden-files
+        name: forbidden files
+        entry: found Copier update rejection files; review them and remove them
+        language: fail
+        files: "\\.rej$"
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v4.4.0
     hooks:
@@ -15,8 +23,10 @@ repos:
       - id: pretty-format-json
         args: [--autofix, --indent=2]
       - id: trailing-whitespace
+      - id: check-merge-conflict
+        args: [--assume-in-merge]
   - repo: https://github.com/igorshubovych/markdownlint-cli
-    rev: v0.36.0
+    rev: v0.37.0
     hooks:
       - id: markdownlint
   - repo: https://github.com/citation-file-format/cffconvert

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning].
 
 ## [Unreleased]
 
+### Added
+
+- Use pre-commit to prevent adding .rej files and ongoing merge conflicts
+
 ## [0.1.5] - 2023-09-22
 
 ### Fixed