Scan Issues (#470)

* Fixed an oversight where unique file extensions for KavitaStats wouldn't ignore case.

* Fixed an issue where series were getting removed then re-added due to bad logic when comparing if the series from disk matched the series in DB based on format.

API/Data/FileRepository.cs

@@ -20,7 +20,7 @@ namespace API.Data
         {
             var fileExtensions = await _dbContext.MangaFile
                 .AsNoTracking()
-                .Select(x => x.FilePath)
+                .Select(x => x.FilePath.ToLower())
                 .Distinct()
                 .ToArrayAsync();
 
@@ -32,4 +32,4 @@ namespace API.Data
             return uniqueFileTypes;
         }
     }
-}
+}