tools: require meson 1.2.3

This is necessary to work on machines with Python 3.12. libplacebo fails to detect python with meson 1.2.0.

1.2.3 is the first to support Python 3.12 [1]

We download 1.4.2 since 3f852923.

[1] https://mesonbuild.com/meson-python/reference/meson-compatibility.html