python: use vendored tomli

Debian only introduced tomli in the bookworm release.  Use a
vendored wheel to avoid requiring a package that is only in
bullseye-backports and is also absent in Ubuntu 20.04.

While at it, fix an issue in the vendor.py scripts which does
not add a newline after each package and hash.

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

configure

@@ -1018,6 +1018,12 @@ fi
 python="$python -B"
 mkvenv="$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
 if ! $mkvenv ensure \
      --dir "${source_path}/python/wheels" \
      --diagnose "meson" \

python/scripts/vendor.py

@@ -43,13 +43,16 @@ def main() -> int:
     packages = {
         "meson==0.63.3":
         "d677b809c4895dcbaac9bf6c43703fcb3609a4b24c6057c78f828590049cf43a",
+
+        "tomli==2.0.1":
+        "939de3e7a6161af0c887ef91b7d41a53e7c5a1ca976325f429cb46ea9bc30ecc",
     }
 
     vendor_dir = Path(__file__, "..", "..", "wheels").resolve()
 
     with tempfile.NamedTemporaryFile(mode="w", encoding="utf-8") as file:
         for dep_spec, checksum in packages.items():
-            file.write(f"{dep_spec} --hash=sha256:{checksum}")
+            print(f"{dep_spec} --hash=sha256:{checksum}", file=file)
         file.flush()
 
         cli_args = [