fix dependencies in CI

Running "apt-get install" without a preceding "apt-get update" has
started failing on GitHub Actions, eg:

https://github.com/scottlamb/moonfire-nvr/runs/1750609817

I believe the problem is that older packages have been removed from
the mirror, and the update will fix this, as described here:

https://github.com/actions/virtual-environments/issues/675#issuecomment-671057659

Also, I was using ncurses version 5 packages, when I should be using the
unversioned default. Same in the build guide.

.github/workflows/ci.yml

@@ -30,7 +30,7 @@ jobs:
           target
         key: ${{ matrix.rust }}-cargo-${{ hashFiles('**/Cargo.lock') }}
     - name: Install dependencies
-      run: sudo apt-get install libavcodec-dev libavformat-dev libavutil-dev libncurses5-dev libncursesw5-dev libsqlite3-dev pkgconf
+      run: sudo apt-get update && sudo apt-get install libavcodec-dev libavformat-dev libavutil-dev libncurses-dev libsqlite3-dev pkgconf
     - name: Install Rust
       uses: actions-rs/toolchain@v1
       with:

guide/build.md

@@ -124,8 +124,7 @@ $ sudo apt-get install \
                libavcodec-dev \
                libavformat-dev \
                libavutil-dev \
-               libncurses5-dev \
-               libncursesw5-dev \
+               libncurses-dev \
                libsqlite3-dev \
                pkgconf \
                sqlite3 \