Set the state.toml filename based upon --select-output (#206)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: AA-Turner

build_docs.py

@@ -937,7 +937,10 @@ def should_rebuild(self):
         return False
 
     def load_state(self) -> dict:
-        state_file = self.build_root / "state.toml"
+        if self.select_output is not None:
+            state_file = self.build_root / f"state-{self.select_output}.toml"
+        else:
+            state_file = self.build_root / "state.toml"
         try:
             return tomlkit.loads(state_file.read_text(encoding="UTF-8"))[
                 f"/{self.language.tag}/{self.version.name}/"
@@ -950,7 +953,10 @@ def save_state(self, build_start: dt, build_duration: float, trigger: str):
 
         Using this we can deduce if a rebuild is needed or not.
         """
-        state_file = self.build_root / "state.toml"
+        if self.select_output is not None:
+            state_file = self.build_root / f"state-{self.select_output}.toml"
+        else:
+            state_file = self.build_root / "state.toml"
         try:
             states = tomlkit.parse(state_file.read_text(encoding="UTF-8"))
         except FileNotFoundError: