Accept 403 response status on link checking

This is returned on cloudflare protected sites where they do "human
verification". For example, the iohk.io website containing the research
paper library we often link to.

Author: ch1bo

.github/workflows/link-check-config.json

@@ -3,5 +3,5 @@
   "retryOn429": true,
   "retryCount": 5,
   "fallbackRetryDelay": "30s",
-  "aliveStatusCodes": [200, 206]
+  "aliveStatusCodes": [200, 206, 403]
 }

src/consensus/chainsel.md

@@ -259,12 +259,6 @@ Once the node finishes syncing with the network, this rule gracefully converges
 into the usual length-based comparison used in Praos, so the node can safely
 switch to running only Ouroboros Praos.
 
-<!-- iohk.io links return 403 "if you are not a human" -->
-
-<!-- markdown-link-check-disable -->
-
-<!-- markdown-link-check-enable -->
-
 [bft]: https://iohk.io/en/research/library/papers/ouroboros-bft-a-simple-byzantine-fault-tolerant-consensus-protocol/
 [classic]: https://iohk.io/en/research/library/papers/ouroboros-a-provably-secure-proof-of-stake-blockchain-protocol/
 [genesis]: https://iohk.io/en/research/library/papers/ouroboros-genesis-composable-proof-of-stake-blockchains-with-dynamic-availability/

src/network/node-to-node/chainsync/README.md

@@ -148,9 +148,5 @@ for the particular era:
 {{#include header.cddl}}
 ```
 
-<!-- iohk.io links return 403 "if you are not a human" -->
-
-<!-- markdown-link-check-disable-next-line -->
-
 [k-secparam]: ../../../consensus/chainsel.md#the-k-security-parameter
 [pipelining]: https://iohk.io/en/blog/posts/2022/02/01/introducing-pipelining-cardanos-consensus-layer-scaling-solution/