typing improvements on level and fill_value in Series.eq (#54729)

* typing improvements on level and fill_value in Series.eq

* minor fix

* Typing improvements freq in Series.to_timestamp

* change typing from str to Frequency

---------

Co-authored-by: color455nm <color455nm@example.com>

Author: color455nm

pandas/core/series.py

@@ -166,6 +166,7 @@
         DtypeBackend,
         DtypeObj,
         FilePath,
+        Frequency,
         IgnoreRaise,
         IndexKeyFunc,
         IndexLabel,
@@ -5630,7 +5631,7 @@ def dropna(
 
     def to_timestamp(
         self,
-        freq=None,
+        freq: Frequency | None = None,
         how: Literal["s", "e", "start", "end"] = "start",
         copy: bool | None = None,
     ) -> Series:
@@ -5945,7 +5946,13 @@ def _flex_method(self, other, op, *, level=None, fill_value=None, axis: Axis = 0
             return op(self, other)
 
     @Appender(ops.make_flex_doc("eq", "series"))
-    def eq(self, other, level=None, fill_value=None, axis: Axis = 0) -> Series:
+    def eq(
+        self,
+        other,
+        level: Level | None = None,
+        fill_value: float | None = None,
+        axis: Axis = 0,
+    ) -> Series:
         return self._flex_method(
             other, operator.eq, level=level, fill_value=fill_value, axis=axis
         )