Update required deal.II version

README.md

@@ -21,7 +21,7 @@ We require:
     -  **clang** version >= 15
     -  **icc** (Intel compiler) 2021.2
 - **openMPI** version  >= 4.0.3
-- **deal.II** version >= 9.5
+- **deal.II** version >= 9.6
 
 The library **polyDEAL** employs **deal.II** as main third-party library. As **deal.II** itself depends on other external libraries for many functionalities, we strongly suggest to download and install deal.II following the instructions available at https://www.dealii.org/download.html and https://www.dealii.org/developer/readme.html. The minimal set of other external libraries that we require are: **METIS**, **p4est**, **Trilinos**. All of them should be compiled against  MPI during the installation phase of deal.II.