Update env cpu for failing tests

environment-cpu.yml

@@ -2,7 +2,9 @@ name: flatland-baseline-cpu-env
 dependencies:
     - conda-build
     - python=3.7
-    - pip=20.0
+    - libgcc
+    - pip
+    - cairo
     - pip:
         - flatland-rl==2.2.1
         - CairoSVG==2.4.2
@@ -12,3 +14,4 @@ dependencies:
         - wandb==0.9.2
         - ray[rllib]==0.8.5
         - tensorflow==2.1.0
+