Fix inconsistent dependency caps

[kiersten-stokes]

Closes #2430

What changes were proposed in this pull request?

Removes the cap for:

• jupyter_core (former cap on v5 was unnecessary as Elyra works close enough with this repo to be aware of breaking changes)

• minio (former cap on v8 didn't exist)

• pyyaml (former cap on v6 should not introduce any breaking changes; tested and confirmed)

• requests (former cap on v3 didn't exist; future releases, however, may include breaking changes)

How was this pull request tested?

Tests are passing. Also manually tested to ensure that pyyaml v6 has the expected behavior.

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[elyra-bot]

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[ptitzler]

LGTM

[kevin-bates]

LGTM - thanks.