Removed old preprocessor submodule

Author: AnastaZIuk

.gitmodules

@@ -90,9 +90,6 @@
 [submodule "3rdparty/implot"]
 	path = 3rdparty/implot
 	url = git@github.com:Devsh-Graphics-Programming/implot.git
-[submodule "3rdparty/boost/preprocessor"]
-	path = 3rdparty/boost/preprocessor
-	url = git@github.com:Devsh-Graphics-Programming/preprocessor.git
 [submodule "tests"]
 	path = tests
 	url = git@github.com:Devsh-Graphics-Programming/Nabla-Continous-Integration-Python-Framework.git