Update cppcheck to 2.1
#build last cppcheck 1.86 (for Travis)
cd ..
-git clone -b "1.86" --depth 1 https://github.com/danmar/cppcheck.git
+git clone -b "2.1" --depth 1 https://github.com/danmar/cppcheck.git
cd cppcheck
cmake .
make -j$(nproc) all
