[MS-537] The 'expiration' field in the 'License' class is now nullable to reflect the BFSID API

[alexandr-simprints]

The BFSID might return the face SDK license response with no expiration field:

{
  "VENDOR": {
    "vendor": "VENDOR",
    "data": "{...}"
}

Reflecting this in the License class so that the parsing won't fail

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
90.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud