Add elixir to pre-commit

.pre-commit-config.yaml

@@ -1,7 +1,33 @@
 repos:
--   repo: https://github.com/pre-commit/pre-commit-hooks
+  # Elixir config
+  - repo: local
+    hooks:
+      - id: mix-format
+        name: 'elixir: mix format'
+        entry: mix format --check-formatted
+        language: system
+        files: \.exs*$
+      - id: mix-lint
+        name: 'elixir: mix credo'
+        entry: mix credo --strict
+        language: system
+        pass_filenames: false
+        files: \.exs*$
+      - id: mix-compile
+        name: 'elixir: mix compile'
+        entry: mix compile --force --warnings-as-errors
+        language: system
+        pass_filenames: false
+        files: \.ex$
+
+  # Standard pre-commit hooks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v2.3.0
     hooks:
-    -   id: check-yaml
-    -   id: end-of-file-fixer
-    -   id: trailing-whitespace
+      - id: check-yaml
+      - id: check-merge-conflict
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+      - id: check-merge-conflict
+      - id: no-commit-to-branch
+        args: [-b, master, -b, develop]