net: switch to signet DNS seed

This commit also drops a seed node that no longer exists.

Author: Sjors

src/chainparams.cpp

@@ -280,8 +280,10 @@ class SigNetParams : public CChainParams {
 
         if (!args.IsArgSet("-signetchallenge")) {
             bin = ParseHex("512103ad5e0edad18cb1f0fc0d28a3d4f1f3e445640337489abb10404f2d1e086be430210359ef5021964fe22d6f8e05b2463c9540ce96883fe3b278760f048f5189f2e6c452ae");
+            vSeeds.emplace_back("seed.signet.bitcoin.sprovoost.nl");
+
+            // TODO: remove hardcoded nodes once there are more DNS seeds
             vSeeds.emplace_back("178.128.221.177");
-            vSeeds.emplace_back("2a01:7c8:d005:390::5");
             vSeeds.emplace_back("v7ajjeirttkbnt32wpy3c6w3emwnfr3fkla7hpxcfokr3ysd3kqtzmqd.onion:38333");
 
             consensus.nMinimumChainWork = uint256S("0x0000000000000000000000000000000000000000000000000000008546553c03");