Remove unnecessary Cython directives

Author: thalassemia

src/stochastic_arrow/arrow.pxd

@@ -1,5 +1,2 @@
-# cython: language_level=3str
-# cython: freethreading_compatible = True
-
-# This file works around a Cython 3.0.0a1+ error on arrowhead.pyx:
+# This file works around a Cython 3.0.0a1 error on arrowhead.pyx:
 #    stochastic_arrow/arrowhead.pyx:14:0: 'arrow.pxd' not found

src/stochastic_arrow/mersenne.pxd

@@ -1,6 +1,3 @@
-# cython: language_level=3str
-# cython: freethreading_compatible = True
-
 from libc.stdint cimport uint32_t
 
 

src/stochastic_arrow/obsidian.pxd

@@ -1,6 +1,3 @@
-# cython: language_level=3str
-# cython: freethreading_compatible = True
-
 from libc.stdint cimport int64_t, uint32_t
 
 from mersenne cimport MTState