[chore] Upgrade to Go 1.24 (#4187)

* Set `go.mod` to 1.24 now that it's been out for 3 months.
* Update all the test to use `testing.T.Context()`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4187
Co-authored-by: Daenney <git@noreply.sourcery.dny.nu>
Co-committed-by: Daenney <git@noreply.sourcery.dny.nu>

internal/processing/media/getemoji_test.go

@@ -18,7 +18,6 @@
 package media_test
 
 import (
-	"context"
 	"testing"
 
 	"github.com/stretchr/testify/suite"
@@ -29,7 +28,7 @@ type GetEmojiTestSuite struct {
 }
 
 func (suite *GetEmojiTestSuite) TestGetCustomEmojis() {
-	emojis, err := suite.mediaProcessor.GetCustomEmojis(context.Background())
+	emojis, err := suite.mediaProcessor.GetCustomEmojis(suite.T().Context())
 
 	suite.NoError(err)
 	suite.Equal(1, len(emojis))