Actually apply the pre-commit fixers to the codebase.

This can be redone manually with
`pre-commit run --all`

While the pre-commit hook could be merged to run locally,
it is much cleaner to align all the files to best-practice
syntax in a single commit. It is also required for server-side
validation.

server/file_cache.go

@@ -3,13 +3,14 @@ package server
 import (
 	"errors"
 	"fmt"
-	"heckel.io/ntfy/util"
 	"io"
 	"os"
 	"path/filepath"
 	"regexp"
 	"sync"
 	"time"
+
+	"heckel.io/ntfy/util"
 )
 
 var (