PersistentVolumeClaims will remain unbound indefinitely if a matching PersistentVolume does not exist. The PersistentVolume is matched with accessModes and capacity. In this case capacity the PV is 10Gi whereas PVC has capacity of 3Gi.
The capacity in the PV needs to same as in the claim i.e 3Gi to fix the unbound immediate PersistentVolumeClaims issue.