develop branch: Compilation error

[Fran-FC]

Describe the Bug
Error compiling devel branch, I don't know if I have to modify the Makefile.

Steps to Reproduce

1. In develop branch, follow the build instructions for Linux https://github.com/cyberbotics/webots/wiki/Linux-installation/
2. make instruction fails

Expected behavior
Should compìle

Screenshots
Chunk of the output:

../../bin/qt/moc: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.28' not found (required by ../../bin/qt/moc)
# compiling nodes/WbAbstractCamera.cpp
# compiling scene_tree/WbAddInertiaMatrixDialog.cpp
# compiling scene_tree/WbAddNodeDialog.cpp
# compiling engine/WbAnimationRecorder.cpp
# compiling app/WbApplication.cpp
# compiling nodes/WbBackground.cpp
# compiling nodes/WbBallJoint.cpp
# compiling nodes/WbBallJointParameters.cpp
# compiling nodes/WbBaseNode.cpp
# compiling nodes/WbBasicJoint.cpp
# compiling nodes/WbBillboard.cpp
# compiling scene_tree/WbBoolEditor.cpp
In file included from ../../include/qt/QtCore/QtCore/qdir.h:44:0,
                 from ../../include/qt/QtCore/QtCore/QDir:1,
                 from scene_tree/WbAddNodeDialog.hpp:22,
                 from scene_tree/WbAddNodeDialog.cpp:15:
../../include/qt/QtCore/QtCore/qfile.h:49:10: fatal error: filesystem: No such file or directory
 #include <filesystem>
          ^~~~~~~~~~~~
compilation terminated.

System

• Operating System: Linux 5.4.0-107-generic 18.04.1-Ubuntu
• Graphics Card: Nvidia GTX 1660

[omichel]

The develop branch is not compatible with Ubuntu 18.04, you should upgrade to Ubuntu 20.04.