[CI] Enable workflow dispatch for Sistent package auto-bumper

[leecalcote]

Current Behavior

On rare occasions it is helpful to be able to manually dispatch this workflow.

Desired Behavior

Ideally, it accepts release tag as an optional input, using the latest release tag when no input is given.

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Contributor Guides and Resources

• 🛠 Meshery Build & Release Strategy
• 🎨 Wireframes and designs for Sistent site in Figma (open invite)
• 🙋🏾🙋🏼 Questions: Layer5 Discussion Forum and Layer5 Community Slack

[Aditya-PS-05]

@leecalcote , can you assign me this issue?