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/base/models/giftcards.py

@@ -55,7 +55,7 @@ class GiftCard(LoggedModel):
         validators=[
             RegexValidator(
                 regex="^[a-zA-Z0-9][a-zA-Z0-9.-]+$",
-                message=_("The giftcard code may only contain letters, numbers, dots and dashes."),
+                message=_("The gift card code may only contain letters, numbers, dots and dashes."),
             )
         ],
     )