Fix test failures on rust < 1.59

Author: fornwall

src/manifest.rs

@@ -127,7 +127,7 @@ pub fn split_input(
 
 #[rustversion::before(1.59)]
 #[cfg(test)]
-pub const STRIP_SECTION: &str = "";
+pub const STRIP_SECTION: &str = "\n";
 #[rustversion::since(1.59)]
 #[cfg(test)]
 pub const STRIP_SECTION: &str = r##"