Bump mypy from 1.3.0 to 1.4.0

Bumps [mypy](https://github.com/python/mypy) from 1.3.0 to 1.4.0.
- [Commits](python/mypy@v1.3.0...v1.4.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

mypy-requirements.txt

@@ -1,4 +1,4 @@
-mypy==1.3.0  # update pyproject.toml as well
+mypy==1.4.0  # update pyproject.toml as well
 black>=19.10b0
 types-pkg_resources
 types-requests

pyproject.toml

@@ -3,7 +3,7 @@ requires = [
     "setuptools>=45",
     "setuptools_scm[toml]>=6.2",
     'mypy==0.971; python_version == "3.6"',  # last version for Python 3.6
-    'mypy==1.3.0; python_version >= "3.7"',  # update mypy-requirements as well
+    'mypy==1.4.0; python_version >= "3.7"',  # update mypy-requirements as well
     "black>=19.10b0",
     "types-pkg_resources",
     "types-requests",