Update publish workflows to reflect updated repo structure

Author: jeskew

.github/workflows/publish.yml

@@ -23,11 +23,13 @@ jobs:
     - name: Cargo Publish (Dry Run)
       if:  ${{ inputs.dry-run == true || inputs.dry-run == 'true' }} 
       run: cargo publish --dry-run --token ${CRATES_TOKEN} -p antithesis_sdk
+      working-directory: ./lib
       env:
         CRATES_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
 
     - name: Cargo Publish
       if:   ${{ inputs.dry-run != true && inputs.dry-run != 'true' }} 
       run: cargo publish --token ${CRATES_TOKEN} -p antithesis_sdk
+      working-directory: ./lib
       env:
         CRATES_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}