fix(types): allow running from Python 3.7

Author: henryiii

src/boost_histogram/_core/accumulators.pyi

@@ -19,7 +19,7 @@ class WeightedSum(_BaseAccumulator):
     def value(self) -> float: ...
     @property
     def variance(self) -> float: ...
-    def __iadd__(self: T, val: float, /) -> T: ...
+    def __iadd__(self: T, arg0: float) -> T: ...
     def fill(self: T, value: ArrayLike, variance: ArrayLike | None = None) -> T: ...
     @staticmethod
     def _make(self: T, a: ArrayLike, b: ArrayLike) -> T: ...
@@ -32,7 +32,7 @@ class Sum(_BaseAccumulator):
     def __init__(self, value: float | None) -> None: ...
     @property
     def value(self) -> float: ...
-    def __iadd__(self: T, val: float, /) -> T: ...
+    def __iadd__(self: T, arg0: float) -> T: ...
     def fill(self: T, value: ArrayLike) -> T: ...
     @property
     def _small(self) -> float: ...
@@ -63,11 +63,11 @@ class WeightedMean(_BaseAccumulator):
     def fill(self: T, value: ArrayLike, *, weight: ArrayLike | None = None) -> T: ...
     @staticmethod
     def _make(
-        self: T, a: ArrayLike, b: ArrayLike, c: ArrayLike, d: ArrayLike, /
+        self: T, arg0: ArrayLike, arg1: ArrayLike, arg2: ArrayLike, arg3: ArrayLike
     ) -> T: ...
     @staticmethod
     def _array(
-        self: T, a: ArrayLike, b: ArrayLike, c: ArrayLike, d: ArrayLike, /
+        self: T, arg0: ArrayLike, arg1: ArrayLike, arg2: ArrayLike, arg3: ArrayLike
     ) -> T: ...
     def __getitem__(self, key: str) -> float: ...
     def __setitem__(self, key: str, value: float) -> None: ...
@@ -87,12 +87,8 @@ class Mean(_BaseAccumulator):
     ) -> T: ...
     def fill(self: T, value: ArrayLike, *, weight: ArrayLike | None = None) -> T: ...
     @staticmethod
-    def _make(
-        self: T, a: ArrayLike, b: ArrayLike, c: ArrayLike, d: ArrayLike, /
-    ) -> T: ...
+    def _make(self: T, arg0: ArrayLike, arg1: ArrayLike, arg2: ArrayLike) -> T: ...
     @staticmethod
-    def _array(
-        self: T, a: ArrayLike, b: ArrayLike, c: ArrayLike, d: ArrayLike, /
-    ) -> T: ...
+    def _array(self: T, arg0: ArrayLike, arg1: ArrayLike, arg2: ArrayLike) -> T: ...
     def __getitem__(self, key: str) -> float: ...
     def __setitem__(self, key: str, value: float) -> None: ...