CI: register qemu-user-static to compile static ubxtool binaries

.github/workflows/ubxtool.yml

@@ -11,6 +11,8 @@ jobs:
     - uses: actions/checkout@v2
     - name: submodules
       run: git submodule update --init --recursive --depth=1
+    - name: register qemu-user-static
+      run: sudo docker run --rm --interactive --privileged multiarch/qemu-user-static:register --reset
     - name: build-ubxtool
       run: ./build-ubxtool ${{ matrix.mach }} static
     - uses: actions/upload-artifact@v1