tag mpw-9e: referenced pdk missing sram maglefs

[d-m-bailey]

The default OPEN_PDK_COMMIT in the Makefile references a pdk 78b7bc32ddb4b6f14f76883c2e2dc5b5de9d1cbc that is missing libs.ref/sky130_sram_macros/maglef directory.

$ volare ls
In <pdk_root>/volare/sky130/versions:
└── 78b7bc32ddb4b6f14f76883c2e2dc5b5de9d1cbc (2023.07.10) (enabled)

$ ls $PDK_ROOT/$PDK/libs.ref/sky130_sram_macros/
gds  lef  lib  spice  verilog

This will cause the sram abstraction in the drc precheck to fail resulting in precheck not completing.