workflows/release-tasks: Always run apt-get update before installing deps

[tstellar]

Summary

There is a bug in the package tree of on the default images that
causes some dependencies not to be found. Running apt-get gets us
the latest package lists rather than relying on the default lists
in the GitHub Runner imgae, which can be up to a week old.

Running apt-get update before intstalling packages is also recommended in
the official github documentation:

https://docs.github.com/en/actions/using-github-hosted-runners/customizing-github-hosted-runners#installing-software-on-ubuntu-runners

.github/workflows/release-tasks.yml

steps:
         run: |
           test "${{ github.actor }}" = "tstellar" || test "${{ github.actor }}" = "tru"
           echo "${{ github.ref_name }}" | grep -e '^llvmorg-[0-9]\+\.[0-9]\+\.[0-9]\+\(-rc[0-9]\+\)\?$'
           release_version=$(echo "${{ github.ref_name }}" | sed 's/llvmorg-//g')
           echo "release-version=$release_version" >> $GITHUB_OUTPUT
 
       - name: Install Dependencies
         run: |
+          sudo apt-get update \
           sudo apt-get install -y \
               doxygen \
               graphviz \
               python3-github \
               python3-recommonmark \
               python3-sphinx \
               ninja-build \
               texlive-font-utils