python: Install pygdbmi in meson's venv

The upcoming changes in the reverse_debugging functional test to remove
Avocado as a dependency will require pygdbmi for interacting with GDB,
so install it in meson's venv (located in the build dir's pyvenv/).

Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Message-ID: <20251003141820.85278-3-gustavo.romero@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

pythondeps.toml

@@ -33,3 +33,4 @@ sphinx_rtd_theme = { accepted = ">=0.5", installed = "1.2.2" }
 
 [testdeps]
 qemu.qmp = { accepted = ">=0.0.3", installed = "0.0.3" }
+pygdbmi = { accepted = ">=0.11.0.0", installed = "0.11.0.0" }