Update tests to include multiple signatures

sample.narinfo

@@ -8,3 +8,4 @@ NarSize: 11374872
 References: mhhlymrg2m70r8h94cwhv2d7a0c8l7g6-glibc-2.34-210 ppn8983d9b5r6k7mnhkbg6rqw7vgl1ij-libyaml-0.2.5 qm2lv1gpbyn0rsfai40cbvj3h4gz69yc-bash-5.1-p16 sn0w3f12547crckss4ybmnxmi29gpgq7-perl-5.34.1 zzxrhj9056vjlanfjkinvhd7458yc2z8-liblouis-3.22.0
 Deriver: dlxmsgfc0am35fh0kiy88zqr91x2dn5j-liblouis-3.22.0.drv
 Sig: cache.nixos.org-1:BJ5QGcOta2s76XC6sep9DbAv0x3TILh3hHSKyR+9rFWYuBDTWdHs1KHeUEpw2espE/zPPBp2yURO6/J4Dhf9DQ==
+Sig: fake-test-sig-1:BJ5QGcOta2s76XC6sep9DbAv0x3TILh3hHSKyR+9rFWYuBDTWdHs1KHeUEpw2espE/zPPBp2yURO6/J4Dhf9DQ==

src/narinfo/from_str.rs

@@ -121,6 +121,10 @@ mod tests {
 		assert_eq!(sig.key_name, "cache.nixos.org-1");
 		assert_eq!(sig.sig, "BJ5QGcOta2s76XC6sep9DbAv0x3TILh3hHSKyR+9rFWYuBDTWdHs1KHeUEpw2espE/zPPBp2yURO6/J4Dhf9DQ==");
 
-		assert!(info.sigs.len() == 1);
+		let sig = &info.sigs[1];
+		assert_eq!(sig.key_name, "fake-test-sig-1");
+		assert_eq!(sig.sig, "BJ5QGcOta2s76XC6sep9DbAv0x3TILh3hHSKyR+9rFWYuBDTWdHs1KHeUEpw2espE/zPPBp2yURO6/J4Dhf9DQ==");
+
+		assert!(info.sigs.len() == 2);
 	}
 }

src/narinfo/to_str.rs

@@ -17,8 +17,8 @@ impl<'a> NarInfo<'a> {
 		write!(w, "\nNarSize: {}", self.nar_size)?;
 		write!(w, "\nReferences: {}", self.references.join(" "))?;
 
-		write!(w, "\nSig: ")?;
 		for sig in self.sigs.iter() {
+			write!(w, "\nSig: ")?;
 			sig.serialize_into(w)?;
 		}