ci: mark linux-class3 job continue-on-error until HDF5 fixes land in develop

Author: brtnfld

.github/workflows/main.yml

@@ -200,9 +200,11 @@ jobs:
       shell: bash
 
   linux-class3:
-    name: Ubuntu GCC with H5ZFP_USE_CLASS3=ON (HDF5 develop)
+    name: Ubuntu GCC with H5ZFP_USE_CLASS3=ON (HDF5 develop — pending upstream merge)
     runs-on: ubuntu-latest
     if: "!contains(github.event.head_commit.message, 'skip-ci')"
+    # H5Z_class3_t is not yet in HDF5 develop; allow failure until the fixes land upstream.
+    continue-on-error: true
 
     steps:
     - name: Install Dependencies