Remove pycodestyle

All the formatting-related warnings from `pycodestyle` are covered by
Black, and almost all of the remaining ones are covered by `pylint`.
Based on that, remove `pycodestyle` so that we don't have to maintain
another set of configuration.

More details on warnings/errors covered by `pycodestyle` below.

---

Here's the big list of pycodestyle error/warning codes:
https://pycodestyle.readthedocs.io/en/latest/intro.html#error-codes. They are
broken down into following categories:

1. Indentation
2. Whitespace
3. Blank line
4. Import
5. Line Length
6. Runtime
7. Deprecation warning
8. Statement

Out of the above, 1-5 are purely formatting related so we don't needd to care
about them. 6 is runtime issues like syntax error that are hard to miss (even
mypy will complain about these). 7 is about deprecation warnings. Half of them
don't apply to us since we only support Python 3.5+ and the other half is
covered by `pylint`.

That leaves us with the "E7*" codes, that pycodestyle groups under "Statement"
heading. After verifying each of them, the only ones that is really not covered
by either Black or Pylint is the following:

*  E731   do not assign a lambda expression, use a def

This sole check does not seem worth keeping another tool.

2 files changed, 0 insertions, 2 deletions

diff --git a/requirements/dev-requirements.in b/requirements/dev-requirements.in
index 8b871073b..cbf44c470 100644
--- a/requirements/dev-requirements.in
+++ b/requirements/dev-requirements.in
@@ -1,5 +1,4 @@
 pylint
-pycodestyle
 pytest >= 3.9
 pytest-datafiles >= 2.0
 pytest-env
diff --git a/requirements/dev-requirements.txt b/requirements/dev-requirements.txt
index c4930181e..bd8449978 100644
--- a/requirements/dev-requirements.txt
+++ b/requirements/dev-requirements.txt
@@ -1,5 +1,4 @@
 pylint==2.3.1
-pycodestyle==2.5.0
 pytest==5.1.2
 pytest-datafiles==2.0
 pytest-env==0.6.2