Drop <3.7 support and add type hints (#59)

- Drop support for Python <3.7
- Bump the pre-commit version used in CI
- Add type hinting and docstrings
- Add mypy to pre-commit config
- Fix typing issues
- Update colors module
  - Update colors module to use uppercase hex codes
  - Add `__lt__` to allow sorting colors by name
- Fix `build_examples.py` to work with color Enum
- Update example badges in `README.md`
- Fix typing issues in server
- Update travis links in `README.md`
- Fix PyPi deployment bug (#60)

build_examples.py

@@ -3,21 +3,20 @@ import anybadge
 if __name__ == "__main__":
 
     print(
-        """| Color Name | Hex Code | Example |
-    | ---------- | -------- | ------- |"""
+        """
+| Color Name    | Hex     | Example |
+| ------------- | ------- | ------- |"""
     )
-    for color, hex in sorted(anybadge.COLORS.items()):
+    for color in sorted(anybadge.colors.Color):
 
-        file = "examples/color_" + color + ".svg"
+        file = "examples/color_" + color.name.lower() + ".svg"
 
         url = "https://cdn.rawgit.com/jongracecox/anybadge/master/" + file
 
-        anybadge.Badge(label="Color", value=color, default_color=color).write_badge(
-            file, overwrite=True
-        )
+        anybadge.Badge(
+            label="Color", value=color.name.lower(), default_color=color.value
+        ).write_badge(file, overwrite=True)
 
         print(
-            "| {color} | {hex} | ![]({url}) |".format(
-                color=color, hex=hex.upper(), url=url
-            )
+            f"| {color.name.lower():<13} | {color.value.upper():<7} | ![]({f'{url})':<84}|"
         )