bpo-43258: Make sqlite3 callback functions static (GH-24574)

diff --git a/Modules/_sqlite/connection.c b/Modules/_sqlite/connection.c
index 39b55fc..81f12e8 100644
--- a/Modules/_sqlite/connection.c
+++ b/Modules/_sqlite/connection.c
@@ -600,7 +600,8 @@ PyObject* _pysqlite_build_py_params(sqlite3_context *context, int argc, sqlite3_
     return args;
 }
 
-void _pysqlite_func_callback(sqlite3_context* context, int argc, sqlite3_value** argv)
+static void
+_pysqlite_func_callback(sqlite3_context *context, int argc, sqlite3_value **argv)
 {
     PyObject* args;
     PyObject* py_func;
@@ -696,7 +697,8 @@ static void _pysqlite_step_callback(sqlite3_context *context, int argc, sqlite3_
     PyGILState_Release(threadstate);
 }
 
-void _pysqlite_final_callback(sqlite3_context* context)
+static void
+_pysqlite_final_callback(sqlite3_context *context)
 {
     PyObject* function_result;
     PyObject** aggregate_instance;