Werk #13309: Update stunnel to 5.60

Component	Other components
Title	Update stunnel to 5.60
Date	Oct 12, 2021
Level	Trivial Change
Class	Bug Fix
Compatibility	Compatible - no manual interaction needed
Checkmk versions & editions	2.1.0b1 Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk MSP (CME)

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