Switch from deprecated "toml" library

Fixes googlefonts#451

setup.py

@@ -45,7 +45,7 @@
         "picosvg>=0.20.4",
         "pillow>=7.2.0",
         "regex>=2020.4.4",
-        "toml>=0.10.1",
+        "tomlkit",
         "ufo2ft[cffsubr]>=2.24.0",
         "ufoLib2>=0.6.2",
         "resvg-cli>=0.22.0.post3",

src/nanoemoji/config.py

@@ -20,9 +20,9 @@
     import importlib_resources as resources  # pytype: disable=import-error
 
 import itertools
+import tomlkit
 from pathlib import Path
 from picosvg.svg_transform import Affine2D
-import toml
 from typing import Any, Iterable, MutableMapping, NamedTuple, Optional, Tuple, Sequence
 
 from nanoemoji import util
@@ -247,6 +247,20 @@ def default(self) -> MasterConfig:
         raise ValueError("Must have a default master")
 
 
+def toml_strip(data):
+    """
+    Workaround for:
+    https://github.com/sdispater/tomlkit/issues/240
+    """
+    new_data = {}
+    for key, val in data.items():
+        if isinstance(val, dict):
+            val = toml_strip(val)
+        if val is not None:
+            new_data[key] = val
+    return new_data
+
+
 def write(dest: Path, config: FontConfig):
     toml_cfg = {
         "family": config.family,
@@ -288,17 +302,19 @@ def write(dest: Path, config: FontConfig):
             for m in config.masters
         },
     }
-    dest.write_text(toml.dumps(toml_cfg))
+    with open(dest, "w") as toml_file:
+        tomlkit.dump(toml_strip(toml_cfg), toml_file)
 
 
 def _resolve_config(
     config_file: Optional[Path] = None,
 ) -> Tuple[Optional[Path], MutableMapping[str, Any]]:
     if config_file is None:
-        with resources.path("nanoemoji.data", _DEFAULT_CONFIG_FILE) as config_file:
-            # no config_dir in this context; bad input if we need it
-            return None, toml.load(config_file)
-    return config_file.parent, toml.load(config_file)
+        # no config_dir in this context; bad input if we need it
+        toml_cfg = resources.files("nanoemoji.data").joinpath(_DEFAULT_CONFIG_FILE).read_text()
+        return None, tomlkit.loads(toml_cfg)
+    with open(config_file) as file:
+        return config_file.parent, tomlkit.load(file)
 
 
 def _resolve_src(relative_base: Optional[Path], src: str) -> Iterable[Path]: