FsCheck.NUnit: indicate compatibility with NUnit v4

Contributors.txt

@@ -1,4 +1,4 @@
-First of all credit should go to John Hughes and Koen Claessen for coming up with the fist version of Haskell's QuickCheck and many fundanmental improvements and ideas. All contributors to QuickCheck are contributors to FsCheck.
+First of all credit should go to John Hughes and Koen Claessen for coming up with the fist version of Haskell's QuickCheck and many fundamental improvements and ideas. All contributors to QuickCheck are contributors to FsCheck.
 
 The same is true, but to a lesser degree, for scalacheck (which is itself a port of QuickCheck to Scala).
 
@@ -14,8 +14,9 @@ David Crocker (first version of replay mechanism, bug fix)
 Howard Mansell (lots of generators and arbitrary instances)
 David Jones (tail recursive version of Gen.sequence, bug fixes)
 Matthew Peacock (gen workflow extensions)
+David Naylor (NUnit 4, sponsored by Counterpoint Dynamics)
 (my sincerest apologies to anyone I overlooked - feel free to protest!)
 
 Thanks to:
 Howard Mansell and team from Credit Suisse, for taking the time to clear up legal stuff and donate code, and being enthusiastic early adopters.
-Everyone that takes the time to report bugs or send feedback.
+Everyone that takes the time to report bugs or send feedback.

Directory.Packages.props

@@ -10,7 +10,7 @@
     <PackageVersion Include="MSTest.TestFramework" Version="2.2.7" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.1" />
     <PackageVersion Include="NuGet.Frameworks" Version="5.11" />
-    <PackageVersion Include="NUnit" Version="[3.13.1,4.0.0)" />
+    <PackageVersion Include="NUnit" Version="[3.13.1,5.0.0)" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.0" />
     <PackageVersion Include="System.Buffers" Version="4.5.1" />
     <PackageVersion Include="System.Collections" Version="4.3" />