[xmlunit/xmlunit.net] cdcda6: use lower case xml extension

[GitHub <no...@gi...>]

  Branch: refs/heads/master
  Home:   https://github.com/xmlunit/xmlunit.net
  Commit: cdcda6054c515587fea5b94dbaa9f2a22c577207
      https://github.com/xmlunit/xmlunit.net/commit/cdcda6054c515587fea5b94dbaa9f2a22c577207
  Author: Stefan Bodewig <ste...@fr...>
  Date:   2017-03-23 (Thu, 23 Mar 2017)

  Changed paths:
    M src/main/net-constraints-nunit2/XMLUnit.NUnit2.Constraints.csproj
    M src/main/net-constraints-nunit3/XMLUnit.NUnit3.Constraints.csproj
    M src/main/net-core/XMLUnit.Core.csproj

  Log Message:
  -----------
  use lower case xml extension