fuzz: `scriptpubkeyman`: heap-buffer-overflow miniscript.cpp in CScript BuildScript

```
$ echo "dHIoJTE3LzwyOzM+LGw6cGsoJTA4KSk=" | base64 --decode > scriptpubkeyman.crash
$ FUZZ=scriptpubkeyman src/test/fuzz/fuzz scriptpubkeyman.crash
...
SUMMARY: AddressSanitizer: heap-buffer-overflow miniscript.cpp in CScript BuildScript<opcodetype, CScript&, opcodetype, CScript&, opcodetype>(opcodetype&&, CScript&, opcodetype&&, CScript&, opcodetype&&)
...
```