Eliminate imports of django.contrib.staticfiles.templatetags

This is dropped in favour of django.templatetags.static in Django 3.0

wagtail/admin/menu.py

@@ -1,7 +1,7 @@
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.forms import Media, MediaDefiningClass
 from django.forms.utils import flatatt
 from django.template.loader import render_to_string
+from django.templatetags.static import static
 from django.utils.safestring import mark_safe
 from django.utils.text import slugify
 

wagtail/admin/templatetags/wagtailadmin_tags.py

@@ -5,9 +5,9 @@ from django.conf import settings
 from django.contrib.admin.utils import quote
 from django.contrib.humanize.templatetags.humanize import intcomma
 from django.contrib.messages.constants import DEFAULT_TAGS as MESSAGE_TAGS
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.template.defaultfilters import stringfilter
 from django.template.loader import render_to_string
+from django.templatetags.static import static
 from django.utils.html import conditional_escape
 from django.utils.safestring import mark_safe
 

wagtail/core/blocks/list_block.py

@@ -1,8 +1,8 @@
 from django import forms
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.core.exceptions import ValidationError
 from django.forms.utils import ErrorList
 from django.template.loader import render_to_string
+from django.templatetags.static import static
 from django.utils.html import format_html, format_html_join
 from django.utils.safestring import mark_safe
 

wagtail/core/blocks/stream_block.py

@@ -3,10 +3,10 @@ from collections import OrderedDict, defaultdict
 from collections.abc import Sequence
 
 from django import forms
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.core.exceptions import NON_FIELD_ERRORS, ValidationError
 from django.forms.utils import ErrorList
 from django.template.loader import render_to_string
+from django.templatetags.static import static
 from django.utils.html import format_html_join
 from django.utils.safestring import mark_safe
 from django.utils.translation import ugettext as _

wagtail/core/blocks/struct_block.py

@@ -1,10 +1,10 @@
 import collections
 
 from django import forms
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.core.exceptions import ValidationError
 from django.forms.utils import ErrorList
 from django.template.loader import render_to_string
+from django.templatetags.static import static
 from django.utils.functional import cached_property
 from django.utils.html import format_html, format_html_join
 

wagtail/tests/testapp/wagtail_hooks.py

@@ -1,6 +1,6 @@
 from django import forms
-from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.http import HttpResponse
+from django.templatetags.static import static
 
 import wagtail.admin.rich_text.editors.draftail.features as draftail_features
 from wagtail.admin.menu import MenuItem