Add buck2 build and run test model to pull.yml (#18)

Summary:
Pull Request resolved: #18

Buck build the demo binary `size_test_all_ops` and export a test model `ModuleLinear.ff`, then run the model.

Differential Revision: D47737752

fbshipit-source-id: eaf0e24434e4693e09abafff819b69fa3ec5fada

Author: larryliu0820

.github/workflows/pull.yml

@@ -27,7 +27,17 @@ jobs:
         # Create the softlink to the workspace as install.sh requires to run from its parent directory
         ln -s "${WORKSPACE}" executorch
         # Install executorch
-        source executorch/install.sh
+        bash executorch/install.sh
+        popd
 
         # Just print out the list of packages for debugging
         pip list
+
+        # Build executorch runtime
+        buck2 build //test:size_test_all_ops
+
+        # Export a test model
+        python3 test/models/export_program --modules=ModuleLinear --outdir=./
+
+        # Run test model
+        buck2 run //test:size_test_all_ops ./ModuleLinear.ff