CVE-2021-32842: Path traversal in SharpZipLib

SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library. A check was added if the destination file is under a destination directory. However, it is not enforced that _baseDirectory ends with slash. If the _baseDirectory is not slash terminated like /home/user/dir it is possible to create a file with a name thats begins as the destination directory one level up from the directory, i.e. /home/user/dir.sh. Because of the file name and destination directory constraints, the arbitrary file creation impact is limited and depends on the use case. fixed this vulnerability.