fix: replace uses of obsolete method `RNGCryptoServiceProvider`

[yihezkel]

Replace insecure obsolete method (new RNGCryptoServiceProvider()) with RandomNumberGenerator.Create() in PkzipClassic, ZipFile and ZipOutputStream.

I certify that I own, and have sufficient rights to contribute, all source code and related material intended to be compiled or integrated with the source code for the SharpZipLib open source product (the "Contribution"). My Contribution is licensed under the MIT License.

[codecov[bot]]

Codecov Report

Merging #766 (8a9dcb9) into master (b5b1b07) will increase coverage by 0.02%. The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master     #766      +/-   ##
==========================================
+ Coverage   74.10%   74.13%   +0.02%     
==========================================
  Files          71       71              
  Lines        8441     8450       +9     
==========================================
+ Hits         6255     6264       +9     
  Misses       2186     2186              

Impacted Files	Coverage Δ
...ICSharpCode.SharpZipLib/Encryption/PkzipClassic.cs	71.02% <0.00%> (ø)
src/ICSharpCode.SharpZipLib/Zip/ZipFile.cs	77.24% <100.00%> (ø)
src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs	87.82% <100.00%> (ø)
...harpCode.SharpZipLib/Encryption/ZipAESTransform.cs	89.09% <0.00%> (ø)
...arpCode.SharpZipLib/Tar/TarExtendedHeaderReader.cs	100.00% <0.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[yihezkel]

See https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.rngcryptoserviceprovider?view=net-6.0 and https://github.com/dotnet/runtime/issues/40169