Replace Travis with GitHub actions and fix many typos (#1657)

* Create django.yml

* Fix working directory

* ..

* .

* ..

* a.

* ..

* .

* Fix typo

* Install hunspell

* maxfail

* Fix install

* .

* Reduce number of typos

* Even less typos

* Postgres debug

* Spelling fixes, yet again

* Postgres with PW

* Fix failing test

* New workflows

* Fix syntax error

* Install gettext

* Test aginst python 3.6 as well

* Clean up strategies

* Add badge, do not ignore migrations

* Use pip cache

src/pretix/control/forms/event.py

@@ -396,7 +396,7 @@ class EventSettingsForm(SettingsForm):
     name_scheme = forms.ChoiceField(
         label=_("Name format"),
         help_text=_("This defines how pretix will ask for human names. Changing this after you already received "
-                    "orders might lead to unexpected behaviour when sorting or changing names."),
+                    "orders might lead to unexpected behavior when sorting or changing names."),
         required=True,
     )
     name_scheme_titles = forms.ChoiceField(