Add yaml-cpp and arrow as dependencies via conan/submodules.

.gitmodules

@@ -12,4 +12,8 @@
 	path = modules/conex
 	url = ../../AirShowerPhysics/cxroot.git
 	branch = master
-        shallow = true
+    shallow = true
+[submodule "externals/arrow"]
+	path = externals/arrow
+	url = https://github.com/apache/arrow
+	shallow = true

conanfile.txt

@@ -4,6 +4,7 @@ catch2/2.13.3
 eigen/3.3.8
 boost/1.74.0
 zlib/1.2.11
+yaml-cpp/0.6.3
 
 [generators]
 cmake

arrow @ d613aa68

+Subproject commit d613aa68789288d3503dfbd8376a41f2d28b6c9d