Pin is-terminal to 0.4.7 to maintain MSRV.

`is-terminal` 0.4.8 updated the MSRV to 1.63 and this crate is
at 1.56, so we have to stick with 0.4.7.

Cargo.toml

@@ -19,7 +19,7 @@ once_cell = "1.8.0"
 unicode-width = "0.1.9"
 
 owo-colors = { version = "3.0.0", optional = true }
-is-terminal = { version = "0.4.0", optional = true }
+is-terminal = { version = "=0.4.7", optional = true } # Locked at 0.4.7 due to MSRV
 textwrap = { version = "0.15.0", optional = true }
 supports-hyperlinks = { version = "2.0.0", optional = true }
 supports-color = { version = "2.0.0", optional = true }