Revert "Remove tmp prefix from tar path"

[magik6k]

Reverts #158 - it breaks the publish CI -> https://app.circleci.com/pipelines/github/filecoin-project/filecoin-ffi/975/workflows/37041e94-3dea-4c02-9878-f2c2369c2531/jobs/5277

...
+ trap '{ rm -rf $__tmp_dir; }' EXIT
+ mkdir /tmp/tmp.GpgYd9uoil/filcrypto
+ find -L . -type f -name filcrypto.h -exec cp -- '{}' /tmp/tmp.GpgYd9uoil/filcrypto ';'
+ find -L . -type f -name libfilcrypto.a -exec cp -- '{}' /tmp/tmp.GpgYd9uoil/filcrypto ';'
+ find -L . -type f -name filcrypto.pc -exec cp -- '{}' /tmp/tmp.GpgYd9uoil/filcrypto ';'
+ tar -czf /tmp/filecoin-ffi-Linux-standard-pairing.tar.gz -C /tmp/tmp.GpgYd9uoil 'filcrypto/*'
tar: filcrypto/*: Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors
+ rm -rf /tmp/tmp.GpgYd9uoil

[cryptonemo]

Ok, this is unnecessary, so I support reverting it. Unfortunate, as it looked like it would 'just work'.