Miniwdl

* [Singularity and Podman available](https://miniwdl.readthedocs.io/en/latest/runner_backends.html) as (beta) alternatives to the Docker daemon for executing task containers
* Fix certain problems initializing struct values from `read_json()` (524 jlumpe)

* Improves robustness of certain file system operations (affects reliability in network file systems with non-idempotent request retry patterns)

This version doesn't update the [initial Singularity support](https://github.com/chanzuckerberg/miniwdl/issues/326#issuecomment-939972070) while we still invite feedback on that.

* Fix parsing of degenerate/empty `call some_task {}` in workflow body
* `miniwdl run --copy-input-files-for some_task` to copy input files selectively (for named tasks only)
* New minor configuration options for scalability tuning (see [default.cfg](https://github.com/chanzuckerberg/miniwdl/blob/main/WDL/runtime/config_templates/default.cfg) for details)

_withdrawn_

Adds initial support for running WDL task containers using [Singularity](https://sylabs.io/singularity/) instead of dockerd. See https://github.com/chanzuckerberg/miniwdl/issues/326#issuecomment-939972070 for further details & instructions. This feature isn't production ready yet, but meant for early testing by motivated users.

[](https://pypi.org/project/miniwdl/) [](https://anaconda.org/conda-forge/miniwdl) **[Getting Started](https://miniwdl.readthedocs.io/en/latest/getting_started.html)**

Maintenance release:

* S3 downloader: with `[download_cli] host_credentials`, ensure boto3 ImportError surfaces to operator (518 CarlosBorroto)
* S3 downloader: increase max attempts in retry logic
* bump dependencies