Update to Cython 3.0a8.

Fixes #1801.

docs/changes/1801.feature

+Update from Cython 3.0a6 to 3.0a8.

pyproject.toml

@@ -21,7 +21,7 @@ requires = [
      # failing in Python 2 (https://travis-ci.org/github/gevent/gevent/jobs/683782800);
      # This was fixed in 3.0a5 (https://github.com/cython/cython/issues/3578)
      # 3.0a6 fixes an issue cythonizing source on 32-bit platforms
-     "Cython >= 3.0a6",
+     "Cython >= 3.0a8",
      # See version requirements in setup.py
      "cffi >= 1.12.3 ; platform_python_implementation == 'CPython'",
      # Python 3.7 requires at least 0.4.14, which is ABI incompatible with earlier

src/gevent/_gevent_c_tracer.pxd

@@ -13,9 +13,9 @@ cdef gmctime
 
 
 cdef class GreenletTracer:
-    cpdef readonly object active_greenlet
-    cpdef readonly object previous_trace_function
-    cpdef readonly Py_ssize_t greenlet_switch_counter
+    cdef readonly object active_greenlet
+    cdef readonly object previous_trace_function
+    cdef readonly Py_ssize_t greenlet_switch_counter
 
     cdef bint _killed
 
@@ -28,16 +28,16 @@ cdef class GreenletTracer:
 
 @cython.internal
 cdef class _HubTracer(GreenletTracer):
-    cpdef readonly object hub
-    cpdef readonly double max_blocking_time
+    cdef readonly object hub
+    cdef readonly double max_blocking_time
 
 
 cdef class HubSwitchTracer(_HubTracer):
-    cpdef readonly double last_entered_hub
+    cdef readonly double last_entered_hub
 
 cdef class MaxSwitchTracer(_HubTracer):
-    cpdef readonly double max_blocking
-    cpdef readonly double last_switch
+    cdef readonly double max_blocking
+    cdef readonly double last_switch
 
     @cython.locals(switched_at=double)
     cpdef _trace(self, str event, tuple args)

src/gevent/_gevent_cgreenlet.pxd

@@ -179,7 +179,7 @@ cdef Waiter
 cdef wait
 cdef iwait
 cdef reraise
-cpdef GEVENT_CONFIG
+cdef GEVENT_CONFIG
 
 
 @cython.final