test: retry zipcrypto password tests once (#614)

This is due to the password check only comparing a single byte (as per the spec), which have a 1/255 chance of actually matching regardless of password.

Author: piksel

test/ICSharpCode.SharpZipLib.Tests/Zip/GeneralHandling.cs

@@ -147,9 +147,11 @@ public void UnsupportedCompressionMethod()
 
 		/// <summary>
 		/// Invalid passwords should be detected early if possible, seekable stream
+		/// Note: Have a 1/255 chance of failing due to CRC collision (hence retried once)
 		/// </summary>
 		[Test]
 		[Category("Zip")]
+		[Retry(2)]
 		public void InvalidPasswordSeekable()
 		{
 			byte[] originalData = null;
@@ -216,9 +218,11 @@ public void ExerciseGetNextEntry()
 
 		/// <summary>
 		/// Invalid passwords should be detected early if possible, non seekable stream
+		/// Note: Have a 1/255 chance of failing due to CRC collision (hence retried once)
 		/// </summary>
 		[Test]
 		[Category("Zip")]
+		[Retry(2)]
 		public void InvalidPasswordNonSeekable()
 		{
 			byte[] originalData = null;