Allow #`[space] in regexes (Unrelated to RT#77522)

```
19:16 <Mouq> r: "abcd" ~~ / ab #`[You don't see me] cd /
19:16 <camelia> rakudo b1d675: OUTPUT«===SORRY!=== Error while compiling
                /tmp/_JkAY_k11Q␤Regex not terminated␤at
                /tmp/_JkAY_k11Q:1␤------> "abcd" ~~ / ab #`[You don't see me]
                cd /⏏<EOL>␤    expecting any of:␤        postfix␤        infix
                stopper␤        infix or…»
19:16 <Mouq> std: "abcd" ~~ / ab #`[You don't see me] cd /
19:16 <camelia> std 7c17586: OUTPUT«ok 00:00 43m␤»
```