TST: disable fatal meson warnings for link-against-local-lib package

This package tests adding RPATH entries via linker arguments. This
functionality is deprecated in Meson but it is used in the wild thus
we should make sure it keeps working.

Author: dnicolodi

tests/packages/link-against-local-lib/pyproject.toml

@@ -8,3 +8,6 @@ requires = ['meson-python']
 
 [tool.meson-python]
 allow-windows-internal-shared-libs = true
+
+[tool.meson-python.args]
+setup = ['--no-fatal-meson-warnings']