Add pre-commit configuration

Pretty standard setup

Worth mentioning that flake8 is set to only run on the diff between current
branch and merge target

This will not work outside of a merge request

.pre-commit-config.yaml

+repos:
+  - repo: meta
+    hooks:
+    -   id: identity
+  - repo: https://github.com/nbQA-dev/nbQA
+    rev: 0.3.6
+    hooks:
+    - id: nbqa-isort
+      additional_dependencies: [isort==5.6.4]
+      args: [--nbqa-mutate]
+    - id: nbqa-flake8
+      additional_dependencies: [flake8==3.8.4]
+      args: [--nbqa-mutate]
+  - repo: https://github.com/kynan/nbstripout
+    rev: 0.3.9
+    hooks:
+      - id: nbstripout
+  - repo: https://github.com/pycqa/isort
+    rev: 5.3.0
+    hooks:
+      - id: isort
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.8.4
+    hooks:
+    - id: flake8
+      entry: bash -c 'git diff $CI_MERGE_REQUEST_TARGET_BRANCH_SHA | flake8 --diff' --
+  - repo: https://github.com/myint/rstcheck
+    rev: 3f92957478422df87bd730abde66f089cc1ee19b  # commit where pre-commit support was added
+    hooks:
+    -   id: rstcheck
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    - id: check-added-large-files
+    - id: check-ast
+    - id: check-json
+    - id: check-yaml
+    - id: check-toml
+    - id: end-of-file-fixer
+    - id: trailing-whitespace
+    - id: check-docstring-first
+    - id: check-merge-conflict
+    - id: mixed-line-ending
+      args: [--fix=lf]