Add null-forgiving operator to name in TarExtractor

Added the null-forgiving operator (`!`) to the `name` variable in the `while` loop condition to suppress potential null reference warnings.  `name` is expected to be non-null at this point in the code becauses of the previous IsNullorEmpty check - however that isn't tagged on netstandard2.0.

Author: gfs

RecursiveExtractor/Extractors/TarExtractor.cs

@@ -70,7 +70,7 @@ public async IAsyncEnumerable<FileEntry> ExtractAsync(FileEntry fileEntry, Extra
                         continue;
                     }
                     // Remove leading ./
-                    while (name.StartsWith($".{Path.DirectorySeparatorChar}"))
+                    while (name!.StartsWith($".{Path.DirectorySeparatorChar}"))
                     {
                         name = name[2..];
                     }
@@ -140,7 +140,7 @@ public IEnumerable<FileEntry> Extract(FileEntry fileEntry, ExtractorOptions opti
                         continue;
                     }
                     // Remove leading ./
-                    while (name.StartsWith($".{Path.DirectorySeparatorChar}"))
+                    while (name!.StartsWith($".{Path.DirectorySeparatorChar}"))
                     {
                         name = name[2..];
                     }