build: add update command in an attempt to mediate slopware's 404 error

Author: VisualEhrmanntraut

.github/workflows/build.yaml

@@ -16,6 +16,7 @@ jobs:
           submodules: true
       - name: Install dependencies
         run: |
+          sudo apt-get update -y
           sudo apt-get install -y build-essential libtool ninja-build pkg-config device-tree-compiler libglib2.0-dev gnutls-bin libjpeg-turbo8-dev libpng-dev libslirp-dev libssh-dev libusb-1.0-0-dev liblzo2-dev libncurses5-dev libpixman-1-dev libsnappy-dev vde2 zstd libgnutls28-dev libgmp10 libgmp3-dev lzfse liblzfse-dev python3-pip
           pip3 install --user --upgrade meson
       - name: Build nettle 3.10.2