try fix windows tests

Author: stefannikolei

tests/ImageSharp.Web.Tests/Caching/PhysicialFileSystemCacheTests.cs

@@ -31,9 +31,9 @@ public void FilePathMatchesReference()
         [InlineData("cacheFolder", null, "/Users/WebRoot", null, "/Users/WebRoot/cacheFolder")]
         [InlineData("cacheFolder", "../Temp", null, "/Users/this/a/root", "/Users/this/a/Temp/cacheFolder")]
 #elif Windows
-        [InlineData("cacheFolder", "C:/Temp", null, null, "C:/Temp/cacheFolder")]
-        [InlineData("cacheFolder", null, "C:/WebRoot", null, "C:/WebRoot/cacheFolder")]
-        [InlineData("cacheFolder", "../Temp", null, "C:/this/a/root", "C:/this/a/Temp/cacheFolder")]
+        [InlineData("cacheFolder", "C:/Temp", null, null, "C:\\Temp\\cacheFolder")]
+        [InlineData("cacheFolder", null, "C:/WebRoot", null, "C:\\WebRoot\\cacheFolder")]
+        [InlineData("cacheFolder", "../Temp", null, "C:/this/a/root", "C:\\this\\a\\Temp\\cacheFolder")]
 #endif
         public void CacheRootFromOptions(string cacheFolder, string cacheRoot, string webRootPath, string contentRootPath, string expected)
         {