Update dependency isort to v5

See merge request !38

Resolve "Rework Hjelp Templates"

Closes #33

See merge request !36

# Conflicts:
#   aleksis/apps/hjelp/templates/hjelp/feedback.html

Resolve "Rating field defaults to 1 star"

Closes #10

See merge request !34

Resolve "Add validator for FAQ"

Closes #22

See merge request !37

Resolve "Fix add_arrows"

Closes #32

See merge request !35

Resolve "Review and fix translation of mail templates"

Closes #27

See merge request !33

Resolve "Make lint clean"

Closes #31

See merge request !32

Resolve "Add validators in menu"

Closes #23

See merge request !31

Resolve "Fix IssueCategory save method"

Closes #28

See merge request !30

Update dependency flake8-black to ^0.2.0

See merge request !29

Enable testsuite and lint

See merge request !28