Allow ImageSpec to be just a string

Author: dannyadair

src/pdfbaker/types.py

@@ -8,14 +8,17 @@
 ]
 
 
-class ImageSpec(TypedDict):
+class ImageDict(TypedDict):
     """Image specification."""
 
     name: str
     type: NotRequired[str]
     data: NotRequired[str]
 
 
+ImageSpec = str | ImageDict
+
+
 class StyleDict(TypedDict):
     """Style configuration."""