Only install pcodec on <3.13

Author: dstansby

.github/workflows/ci.yaml

@@ -61,7 +61,15 @@ jobs:
           conda activate env
           export DISABLE_NUMCODECS_AVX2=""
           # TODO: put back zfpy import when it supports numpy 2.0
-          python -m pip install -v -e .[test,test_extras,msgpack,pcodec]
+          python -m pip install -v -e .[test,test_extras,msgpack]
+
+      - name: Install pcodec
+        if: matrix.python-version != '3.13.0rc2'
+        shell: "bash -l {0}"
+        run: |
+            conda activate env
+            python -m pip install -v pcodec
+
 
       # This is used to test with zfpy, which does not yet support numpy 2.0
       - name: Install older numpy and zfpy