[fpdf2] Restore string default values (#9562)

Cf. #9546

Author: srittau

stubs/fpdf2/fpdf/fpdf.pyi

@@ -301,8 +301,8 @@ class FPDF:
     def set_font_size(self, size: float) -> None: ...
     def set_char_spacing(self, spacing: float) -> None: ...
     def set_stretching(self, stretching: float) -> None: ...
-    def add_link(self, y: float = 0, x: float = 0, page: int = -1, zoom: float | Literal["null"] = ...) -> int: ...
-    def set_link(self, link, y: float = 0, x: float = 0, page: int = -1, zoom: float | Literal["null"] = ...) -> None: ...
+    def add_link(self, y: float = 0, x: float = 0, page: int = -1, zoom: float | Literal["null"] = "null") -> int: ...
+    def set_link(self, link, y: float = 0, x: float = 0, page: int = -1, zoom: float | Literal["null"] = "null") -> None: ...
     def link(
         self, x: float, y: float, w: float, h: float, link: str | int, alt_text: str | None = ..., border_width: int = ...
     ) -> AnnotationDict: ...
@@ -435,8 +435,8 @@ class FPDF:
         y: float | None = None,
         w: float = 0,
         h: float = 0,
-        type: str = ...,
-        link: str = ...,
+        type: str = "",
+        link: str = "",
         title: str | None = None,
         alt_text: str | None = None,
         dims: tuple[float, float] | None = None,