Downgrade to MSVC 14.29 for Qt5 on Windows

Since MSVC 14.37 has been removed from the GitHub hosted runner
image (win22 20240304.2.1), and 14.29 is the next most-recent
MSVC version available (on the GitHub hosted runner image).

Squashed commit of the following:

commit fd7998a
Author: Paul Colby <[email protected]>
Date:   Wed Mar 13 08:36:04 2024 +1100

    Restore the Linux and macOS builds

commit bd84986
Author: Paul Colby <[email protected]>
Date:   Wed Mar 13 08:11:28 2024 +1100

    Use the latest MSVS earlier than 14.38 for Qt5

    Because MSVC 14.38 has many issues with Qt5, and 14.29 is now the
    next-latest MSVC on GitHub hosted runners (win22 20240304.2.1).

    https://github.com/actions/runner-images/blob/main/images/windows/Windows2022-Readme.md

commit eecde34
Author: Paul Colby <[email protected]>
Date:   Wed Mar 13 08:01:12 2024 +1100

    Try the default MSVC for Qt5

    Since MSVC 14.37 was removed from the GitHub hosted runner in
    win22 version 20240304.2.1. See
    actions/runner-images@3d6eedc

    It this doesn't work (probably won't) I'll try pinning an earlier
    MSVC version instead.

.github/workflows/build.yaml

@@ -365,7 +365,7 @@ jobs:
       uses: ilammy/msvc-dev-cmd@v1
       with:
         arch: ${{ matrix.msvcArch }}
-        toolset: ${{ startsWith(matrix.qt, '5') && '14.37' || '' }} # MSVC 14.38+ has many deprecation issues with Qt5.
+        toolset: ${{ startsWith(matrix.qt, '5') && '14.29' || '' }} # MSVC 14.38+ has many deprecation issues with Qt5.
     - name: Build
       env:
         PROJECT_BUILD_ID: ${{ github.run_number }}.win.${{ matrix.arch }}.${{ matrix.tool }}.qt-${{ matrix.qt }}