ci: github: bloaty: add matrix for parallel build in Ubuntu Bionic and Focal

Author: TSC21

.github/workflows/bloaty.yml

@@ -11,9 +11,12 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-    container: px4io/px4-dev-nuttx:2020-03-16
     strategy:
       matrix:
+        container: [
+          "px4io/px4-dev-nuttx-bionic:2020-03-29",
+          "px4io/px4-dev-nuttx-focal:2020-03-29"
+          ]
         config: [
           px4_fmu-v2_default,
           px4_fmu-v4_default,
@@ -23,6 +26,7 @@ jobs:
           px4_fmu-v5x_default,
           px4_io-v2_default,
           ]
+    container: ${{ matrix.container }}
     steps:
     - uses: actions/checkout@v1
       with: