ripgrep: disable hyperlinks by default

As a result of discussion in #2611, it seems prudent to disable
hyperlinks by default. Ideally they would be enabled, but it looks like
some environments may barf on them. Since this is the first release with
hyperlink support, it makes sense to me at least to make users opt into
them. This does not preclude enabling them by default in future
releases.

crates/core/args.rs

@@ -1136,7 +1136,7 @@ impl ArgMatches {
             .wsl_prefix(wsl_prefix());
         let fmt: HyperlinkFormat =
             match self.value_of_lossy("hyperlink-format") {
-                None => "default".parse().unwrap(),
+                None => "none".parse().unwrap(),
                 Some(format) => match format.parse() {
                     Ok(format) => format,
                     Err(err) => {