fix(3276): Use get_template()

The `get_template()` call correctly fetches the template via the engine,
but to get the same template type as the one used in the other branch,
we need to access its template attribute, where the original template is
stored.

The engine template wrap the base template to allow direct
rendering by TemplateResponse, however this conflicts with the "template
via static files" approach taken by Strawberry.

Since I'm unfamiliar with the reasoning for this approach, we'll leave
it in tact.

strawberry/django/views.py

@@ -17,7 +17,7 @@
 from django.http.response import HttpResponse
 from django.template import RequestContext, Template
 from django.template.exceptions import TemplateDoesNotExist
-from django.template.loader import render_to_string
+from django.template.loader import get_template
 from django.template.response import TemplateResponse
 from django.utils.decorators import classonlymethod, method_decorator
 from django.views.decorators.csrf import csrf_exempt
@@ -215,7 +215,7 @@ def dispatch(
 
     def render_graphql_ide(self, request: HttpRequest) -> HttpResponse:
         try:
-            template = Template(render_to_string("graphql/graphiql.html"))
+            template = get_template("graphql/graphiql.html").template
         except TemplateDoesNotExist:
             template = Template(self.graphql_ide_html)
 
@@ -274,7 +274,7 @@ async def dispatch(  # pyright: ignore
 
     async def render_graphql_ide(self, request: HttpRequest) -> HttpResponse:
         try:
-            template = Template(render_to_string("graphql/graphiql.html"))
+            template = get_template("graphql/graphiql.html").template
         except TemplateDoesNotExist:
             template = Template(self.graphql_ide_html)