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/templates/pretixcontrol/pdf/index.html

@@ -207,7 +207,7 @@
                     </div>
                     <div class="row control-group pdf-info">
                         <div class="col-sm-12">
-                            <label>{% trans "Prefered language" %}</label><br>
+                            <label>{% trans "Preferred language" %}</label><br>
                             <select class="form-control" id="pdf-info-locale">
                                 <option value="">{% trans "Order locale" %}</option>
                                 {% for l in locales %}