This is an issue with the installed web certificate rather than TPAM.
The Certificate Authority (CA) that supplied the certificate controls the algorithm used for signing certificates. The CA should be configured to provide SHA-256 certificates. If using an internal Microsoft CA this can be done with the following commands:
certutil -setreg ca\csp\CNGHashAlgorithm SHA256
net stop certsvc
net start certsvc
If using the factory shipped self signed certificate, this should be replaced with a trusted certificate signed via SHA-256.
All versions of TPAM 2.5, support SHA-256 signed certificates..