Re-enable gossipsub internal tests when running CI

minor bonus: add a link in the comments about bearssl issue with
callbacks

libp2p/crypto/chacha20poly1305.nim

@@ -18,6 +18,7 @@
 import bearssl
 
 # have to do this due to a nim bug and raises[] on callbacks
+# https://github.com/nim-lang/Nim/issues/13905
 proc ourPoly1305CtmulRun*(key: pointer; iv: pointer; data: pointer; len: int;
                       aad: pointer; aadLen: int; tag: pointer; ichacha: pointer;
                       encrypt: cint) {.cdecl, importc: "br_poly1305_ctmul_run",

libp2p/protocols/pubsub/gossipsub.nim

@@ -445,7 +445,7 @@ method initPubSub(g: GossipSub) =
   g.heartbeatLock = newAsyncLock()
 
 ## Unit tests
-when isMainModule and not defined(release):
+when isMainModule:
   ## Test internal (private) methods for gossip,
   ## mesh and fanout maintenance.
   ## Usually I wouldn't test private behaviour,