fixup python cache.

ogscm/building_blocks/ogs_base.py

@@ -6,6 +6,7 @@
 import hpccm.config
 from hpccm.building_blocks.base import bb_base
 from hpccm.building_blocks.packages import packages
+from hpccm.building_blocks.pip import pip
 from hpccm.building_blocks.python import python
 from hpccm.common import linux_distro
 from hpccm.primitives.comment import comment
@@ -32,9 +33,10 @@ class ogs_base(bb_base):
         """String representation of the building block"""
         self += comment(__doc__, reformat=False)
         self += python(devel=True, python2=False)
-        pip_install = shell(
+        self += pip(pip="pip3")
+        self += shell(
             _arguments="--mount=type=cache,target=/root/.cache,sharing=locked",
-            commands=[f"pip3 install pre-commit cmake-format"],
+            commands=["pip3 install pre-commit cmake-format"],
         )
         self += packages(ospackages=self.__ospackages, epel=True)
         self += shell(commands=self.__commands)