Github action: PnetCDF requires libtool 2.5.4

Author: wkliao

.github/workflows/pnetcdf_master.yml

@@ -36,7 +36,7 @@ jobs:
           run: |
             set -x
             sudo apt-get update
-            sudo apt-get install automake autoconf libtool libtool-bin m4
+            sudo apt-get install automake autoconf libtool=2.5.4 m4
             # mpich
             # sudo apt-get install mpich
             # zlib