fix: C SSHNPD memory leaks before SSH connection established

[JeremyTubongbanua]

- What I did

• Pinned atsdk commit which is from https://github.com/atsign-foundation/at_c/pull/325
• Removed atlogger_free() since that is not the most recent feature

- How to verify it

valgrind leak summary after starting daemon, pkam authenticating, starting main loop, then Ctrl-C

==194277== LEAK SUMMARY:
==194277==    definitely lost: 0 bytes in 0 blocks
==194277==    indirectly lost: 0 bytes in 0 blocks
==194277==      possibly lost: 0 bytes in 0 blocks
==194277==    still reachable: 0 bytes in 0 blocks
==194277==         suppressed: 223 bytes in 1 blocks

[JeremyTubongbanua]

As of most recent commit of sending this message,

C SSHNPD works with at_c commit hash: 977cf8f51bb93e494b14fedfe3a577f440e45f0e

[JeremyTubongbanua]

Will wait for https://github.com/atsign-foundation/at_c/pull/325 to be pushed to trunk before we push this to trunk

[JeremyTubongbanua]

Will do 1 more pass before I merge @XavierChanth