Fix prompts for running a nightly build/test locally (#62)
RAPIDS CI supports running CI builds locally using the instructions
here: https://docs.rapids.ai/resources/reproducing-ci/
When a build step requires downloading from S3, the tools script will
prompt for the needed environment variable settings.
```
export RAPIDS_BUILD_TYPE=pull-request # or "branch" or "nightly"
export RAPIDS_REPOSITORY=rapidsai/cugraph
export RAPIDS_REF_NAME=pull-request/3258 # or "branch-YY.MM" for "branch"/"nightly" builds
```
The steps for reproducing a `nightly` test were not working and produced
the following result.
```
[rapids-download-conda-from-s3] Local run detected.
[rapids-download-conda-from-s3] NVIDIA VPN connectivity is required to download workflow artifacts.
Enter workflow type (one of: pull-request|branch|nightly): nightly
Suppress this prompt in the future by setting the 'RAPIDS_BUILD_TYPE' environment variable:
export RAPIDS_BUILD_TYPE=nightly
Enter org/repository name (e.g. rapidsai/cudf): rapidsai/cudf
Suppress this prompt in the future by setting the 'RAPIDS_REPOSITORY' environment variable:
export RAPIDS_REPOSITORY=rapidsai/cudf
Enter pull-request number (e.g. 1546): branch-23.08
Suppress this prompt in the future by setting the 'RAPIDS_REF_NAME' environment variable:
export RAPIDS_REF_NAME=pull-request/branch-23.08
Using HEAD commit for artifact commit hash. Overwrite this by setting the 'RAPIDS_SHA' environment variable:
export RAPIDS_SHA=1854ac86d08e545376704959436ec370bdd8117a
/usr/local/bin/rapids-s3-path: line 40: RAPIDS_NIGHTLY_DATE: unbound variable
```
The nightly build requires the `RAPIDS_NIGHTLY_DATE` date in
`YYYY-MM-DD` format and the `RAPIDS_REF_NAME` is expected to be the
branch name.
This PR updates the prompt logic to allow running a nightly build
locally.
