Update pre-commit hooks

[adamchainz]

• Ran pre-commit autoupdate to pull the latest hook version
• Updated the URL for flake8 for its move from GitLab to GitHub (see: https://twitter.com/codewithanthony/status/1378746934928699396)
• Replaced flake8-blind-except with flake8-bugbear. flake8-blind-except was throwing some false positives on re-raised exceptions. flake8-bugbear's rule B001 covers blindly caught exceptions more thoroughly, plus it covers many other best practices.
• UPdated all other flake8 additional_dependencies to their latest versions.

[codecov-io]

Codecov Report

Merging #3 (595bcde) into master (3e8eefb) will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master       #3   +/-   ##
=======================================
  Coverage   83.60%   83.60%           
=======================================
  Files          36       36           
  Lines        3300     3300           
  Branches      471      471           
=======================================
  Hits         2759     2759           
  Misses        373      373           
  Partials      168      168           

Impacted Files	Coverage Δ
gisserver/queries/stored.py	90.21% <100.00%> (ø)

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[adamchainz]

You can also install pre-commit.ci, which is made by the author of pre-commit, to automatically update your hooks every 2 weeks.