Revert Cython upgrade (#54497)

* Revert "CLN: Cython 3 cleanups (#54482)"

This reverts commit a936863.

* Revert "DEPS: Bump cython 3.0 (#54335)"

This reverts commit 4cf63ea.

Author: phofl

asv_bench/asv.conf.json

@@ -41,7 +41,7 @@
     // pip (with all the conda available packages installed first,
     // followed by the pip installed packages).
     "matrix": {
-        "Cython": ["3.0.0"],
+        "Cython": ["0.29.33"],
         "matplotlib": [],
         "sqlalchemy": [],
         "scipy": [],

ci/deps/actions-310.yaml

@@ -6,7 +6,7 @@ dependencies:
 
   # build dependencies
   - versioneer[toml]
-  - cython>=3.0.0
+  - cython>=0.29.33
   - meson[ninja]=1.0.1
   - meson-python=0.13.1