Remove NVCC+clang 3.8 from list of tested compiler

Author: havogt

README.md

@@ -33,7 +33,6 @@ The GridTools libraries are currently nightly tested with the following compiler
 | Compiler | Backend | Tested on |
 | --- | --- | --- |
 | NVCC 9.2 with GNU 5.3 | cuda | Piz Daint |
-| NVCC 9.2 with Clang 3.8.1 | cuda | Piz Daint |
 | GNU 7.3.0 | x86, mc | Piz Daint |
 | Clang 7.0.1 | x86, mc | Piz Daint |