fix: Don't fail fast, only upload hex if no uf2.

.github/workflows/build.yml

@@ -26,6 +26,7 @@ jobs:
     needs: matrix
     name: Build
     strategy:
+      fail-fast: false
       matrix: ${{fromJson(needs.matrix.outputs.matrix)}}
     steps:
       - name: Prepare variables
@@ -80,8 +81,13 @@ jobs:
       - name: Rename artifacts
         run: |
           mkdir build/artifacts
-          if [ -f build/zephyr/zmk.hex ]; then cp build/zephyr/zmk.hex "build/artifacts/${{ steps.variables.outputs.artifact-name }}.hex"; fi
-          if [ -f build/zephyr/zmk.uf2 ]; then cp build/zephyr/zmk.uf2 "build/artifacts/${{ steps.variables.outputs.artifact-name }}.uf2"; fi
+          if [ -f build/zephyr/zmk.uf2 ]
+          then
+            cp build/zephyr/zmk.uf2 "build/artifacts/${{ steps.variables.outputs.artifact-name }}.uf2"
+          elif [ -f build/zephyr/zmk.hex ]
+          then
+            cp build/zephyr/zmk.hex "build/artifacts/${{ steps.variables.outputs.artifact-name }}.hex"
+          fi
       - name: Archive (${{ steps.variables.outputs.display-name }})
         uses: actions/upload-artifact@v2
         with: