[Misc] Use higher TLS version in JwkCache.cpp

Description

This one liner changes the minimum TLS version to TLSv1.2 for fixing the Security Rating within the Sonar Code Analysis.

Checklist

• Documentation reflects the changes made.
• Merge Request title is clear, concise, and suitable as a changelog entry. See this link

References

Quality Gate passed now.

Closes #1253 (closed)