Add pre-commit hook. (#18)

.pre-commit-config.yaml

@@ -0,0 +1,15 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-merge-conflict
+      - id: check-case-conflict
+
+ci:
+  autofix_commit_msg: "[pre-commit.ci] Auto fixes from pre-commit.com hooks."
+  autofix_prs: true
+  autoupdate_commit_msg: "[pre-commit.ci] Pre-commit autoupdate."
+  autoupdate_schedule: quarterly
+  submodules: false

src/dummy.cpp

@@ -1,4 +0,0 @@
-int main()
-{
-  return 0;
-}

src/settings.json

@@ -8214,4 +8214,4 @@
       "default":"255"
     }
   }
-}
+}