Bumped version to OpenMesh 6.1

6 jobs for master
Status Job ID Name Coverage
  Test
passed #4557
Linux
clang-c++11

00:18:21

passed #4559
Linux
clang-c++98

00:18:39

passed #4556
Linux
gcc-c++11

00:04:38

passed #4558
Linux
gcc-c++98

00:04:11

passed #4560
Apple
macos-c++11

00:09:01

passed #4561
Apple
macos-c++98

00:14:12