Revert "python: use vendored tomli"

Now that Ubuntu 20.04 is not included anymore, there is no need to ship
it as part of QEMU; Ubuntu 22.04 includes it and Leap users anyway
need to install all the required dependencies from PyPI.

This mostly reverts commit ec77ee7634de123b7c899739711000fd21dab68b,
with just some changes to the wording.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -955,10 +955,6 @@ mkvenv="$python ${source_path}/python/scripts/mkvenv.py"
 
 # Finish preparing the virtual environment using vendored .whl files
 
-if $python -c 'import sys; sys.exit(sys.version_info >= (3,11))'; then
-    $mkvenv ensure --dir "${source_path}/python/wheels" \
-        'tomli>=1.2.0' || exit 1
-fi
 $mkvenv ensuregroup --dir "${source_path}/python/wheels" \
      ${source_path}/pythondeps.toml meson || exit 1
 

docs/devel/build-system.rst

@@ -185,14 +185,13 @@ Bundled Python packages
 
 Python packages that are **mandatory** dependencies to build QEMU,
 but are not available in all supported distros, are bundled with the
-QEMU sources.  Currently this includes Meson (outdated in CentOS 8
+QEMU sources.  The only one is currently Meson (outdated in Ubuntu
-and derivatives, Ubuntu 20.04 and 22.04, and openSUSE Leap) and tomli
+22.04 and openSUSE Leap).
-(absent in Ubuntu 20.04).
 
-If you need to update these, please do so by modifying and rerunning
+In order to include a new or updated wheel, modify and rerun the
-``python/scripts/vendor.py``.  This script embeds the sha256 hash of
+``python/scripts/vendor.py`` script.  The script embeds the
-package sources and checks it.  The pypi.org web site provides an easy
+sha256 hash of package sources and checks it.  The pypi.org web site
-way to retrieve the sha256 hash of the sources.
+provides an easy way to retrieve the sha256 hash of the sources.
 
 
 Stage 2: Meson

python/scripts/vendor.py

@@ -43,9 +43,6 @@ def main() -> int:
     packages = {
         "meson==1.2.3":
         "4533a43c34548edd1f63a276a42690fce15bde9409bcf20c4b8fa3d7e4d7cac1",
-
-        "tomli==2.0.1":
-        "939de3e7a6161af0c887ef91b7d41a53e7c5a1ca976325f429cb46ea9bc30ecc",
     }
 
     vendor_dir = Path(__file__, "..", "..", "wheels").resolve()