Require at least emoji 2.0, just because the API changed a bit

This plugin doesn't *use* the parts of the API that changed, but there
are still some differences in handling (foreign-language emoji names,
for example) that it's good to explicitly cover by specifying a minimum
here in `sopel-github`'s requirements.

pyproject.toml

@@ -50,7 +50,7 @@ dependencies = [
 
 [project.optional-dependencies]
 emojize = [
-  "emoji>=1.7,<3",
+  "emoji>=2.0,<3",
 ]
 
 [project.urls]