Silences several meson warnings like:
```
../subprojects/equivalent-1.0.1/meson.build:9: WARNING: Project does not target a minimum version but uses feature introduced in '1.3.0': rust_abi arg in static_library.
```
The target of 1.7.0 was chosen since that's the minimal required meson version of the rust components in mesa anyway.
Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38814>
