Bump hammer submodule, update sky130 pdk paths.

[lorenshung]

Bumped hammer submodule, updated sky130 pdk paths.

Related PRs / Issues:

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

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• Did you set main as the base branch?
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• (If applicable) Did you update the conda .conda-lock.yml file if you updated the conda requirements file?
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[jimfangx]

lgtm