less: fix head build (#79143)
less: fix head build (#79143)

Currently the formula uses the `dist` target[1], which includes steps
for creating and `gpg` signing a tarball of the release. This currently
fails with:

```
if [ ! -d ./release ]; then mkdir ./release; fi
Preparing less-590
Creating release/less-590/590.tar.gz
Signing release/less-590/less-590.tar.gz
/bin/sh: gpg: command not found
make: *** [dist] Error 127
```

The proper target seems to be instead `distfiles`, see [2].

[1]: https://github.com/gwsw/less/blob/v590/Makefile.aut#L128
[2]: https://github.com/gwsw/less/issues/139#issuecomment-832064664
mbcoguno/homebrew-core,sjackman/homebrew-core,mbcoguno/homebrew-core,makigumo/homebrew-core,uyjulian/homebrew-core,lemzwerg/homebrew-core,stgraber/homebrew-core,filcab/homebrew-core,uyjulian/homebrew-core,nbari/homebrew-core,Moisan/homebrew-core,nandub/homebrew-core,chrisfinazzo/homebrew-core,sjackman/homebrew-core,makigumo/homebrew-core,cblecker/homebrew-core,adam-moss/homebrew-core,lemzwerg/homebrew-core,mfikes/homebrew-core,nandub/homebrew-core,Moisan/homebrew-core,cblecker/homebrew-core,nbari/homebrew-core,chrisfinazzo/homebrew-core,Linuxbrew/homebrew-core,mfikes/homebrew-core,Linuxbrew/homebrew-core,zyedidia/homebrew-core,mbcoguno/homebrew-core,Homebrew/homebrew-core,Homebrew/homebrew-core,stgraber/homebrew-core,zyedidia/homebrew-core,adam-moss/homebrew-core,filcab/homebrew-core