ci: Install cargo on ubuntu 18.04 container.

ChangeLog:

	* .github/workflows/ccpp.yml: Install cargo for GCC 4.8 job.

Author: CohenArthur

.github/workflows/ccpp.yml

@@ -192,7 +192,8 @@ jobs:
                   g++-4.8 \
                   gcc-4.8-multilib \
                   g++-4.8-multilib \
-                  dejagnu
+                  dejagnu \
+                  cargo
 
     - name: Configure
       run: |