fix: downgrade pyarrow to 20 to work around pyarrow compilation error

related: apache/arrow#47229

Author: xmatthias

requirements.txt

@@ -27,7 +27,9 @@ pycoingecko==3.2.0
 jinja2==3.1.6
 joblib==1.5.1
 rich==14.1.0
-pyarrow==21.0.0; platform_machine != 'armv7l'
+pyarrow==21.0.0; platform_machine != 'armv7l' and platform_machine != "aarch64"
+# TODO: downgrade for aarch64 until https://github.com/apache/arrow/issues/47229 is resolved
+pyarrow==20.0.0;  platform_machine == "aarch64"
 
 # Load ticker files 30% faster
 python-rapidjson==1.21