Fix race condition under non-native bash environments

[tMaxx]

Description

Force treating body as string. Under non-native (e.g. cygwin, mingw) bash environments this may cause a race condition when checking suite status, resulting in a timeout and a 404 that gets passed to user.

Motivation and Context

Fixes #551.

Upgrade notes (if appropriate)

Manual upgrade of aet.sh will be required.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• I have reviewed (and updated if needed) the documentation regarding this change

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I hereby agree to the terms of the AET Contributor License Agreement.

[malaskowski]

Please update CHANGELOG.