Updates for Single calendar booking template

[yepzdk]

Link to issue

#187

Link to ticket

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Description

• Update single calendar booking template.
• Use hsl color instead of oklch for compatibility with older devices.

Screenshot of the result

Checklist

• My code is covered by test cases.
• My code passes our test (all our tests).
• My code passes our static analysis suite.
• My code passes our continuous integration process.

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should be exempt from the list.

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