upload artifacts after CI

.github/workflows/githubci.yml

@@ -30,3 +30,13 @@ jobs:
         GH_REPO_TOKEN: ${{ secrets.GH_REPO_TOKEN }}
         PRETTYNAME : "Adafruit SI1145 Arduino Library"
       run: bash ci/doxy_gen_and_deploy.sh
+
+    - name: upload artifacts
+      uses: actions/upload-artifact@v2
+      with:
+        name: hex files
+        path: |
+            examples/*/build/*/*.hex
+            examples/*/build/*/*.bin
+            examples/*/build/*/*.uf2
+            examples/*/build/*/*.elf