Updated to humble instead of foxy

.github/workflows/rust_and_ros2.yml

@@ -5,21 +5,13 @@ on: [push, pull_request]
 env:
   CARGO_TERM_COLOR: always
 
-jobs:
-  testing_rolling:
+jobs:    
+  testing_humble:
     runs-on: ubuntu-latest
     
     steps:
     - uses: actions/checkout@v2
-    - run: docker build . --file ./tests/Dockerfile --tag r2r_test
-    - run: docker run r2r_test
-    
-  testing_foxy:
-    runs-on: ubuntu-latest
-    
-    steps:
-    - uses: actions/checkout@v2
-    - run: docker build . --file ./tests/Dockerfile_foxy --tag r2r_test
+    - run: docker build . --file ./tests/Dockerfile_humble --tag r2r_test
     - run: docker run r2r_test
 
   testing_galactic: