fix: Shorten the 'name' field in minitar_entry_metadata

Sure, 256 characters might fit in 'path', but because of the way
paths are stored in a tar archive, basenames cannot exceed 100
characters. So, adding space for a null-terminator, this reduces
our 'name' field from 128 bytes to 101.

This change is backwards-compatible since any reasonable application
should not depend on the name field being 128 bytes (this was never
mentioned in any documentation, API.md describes it as 'char[]' without
a fixed length). sizeof(metadata.name) should always be used instead.

minitar.h

@@ -55,7 +55,7 @@ struct minitar_entry_internal
 struct minitar_entry_metadata
 {
     char path[257];
-    char name[128];
+    char name[101];
     char link[101];
     mode_t mode;
     uid_t uid;