overflowing_literals false positive

In a future version of Rust the `overflowing_literals` lint will become deny by default. See rust-lang/rust#55632. When checking for breakage in crates uploaded to crates.io it was discovered that this crate will no longer compile thanks to this lint. The error produced is [here](https://crater-reports.s3.amazonaws.com/pr-55632/try%23dc13be39fae8d4c607889b27de374b52586485a3/gh/BProg.des_chipher_rust/log.txt). This PR should fix the false positive.

src/main.rs

@@ -448,15 +448,15 @@ fn get_48_bit_keys_from_array_of_28_bit_pairs() {
 #[test]
 fn permutation_of_64bit_integer_gives_58_bit() {
     let message_64bit = 0x123456789abcdef;
-    let intial_permutation = 0xcc00ccfff0aaf0aa;
+    let intial_permutation = 0xcc00ccfff0aaf0aa_u64 as i64;
     assert_eq!(intial_permutation, initial_permutation_of_64bit_message(message_64bit));
 }
 
 
 #[cfg(test)]
 #[test]
 fn splitting_key_of_64_bit_into_32_bit_pair() {
-    let key =  0xcc00ccfff0aaf0aa;
+    let key =  0xcc00ccfff0aaf0aa_u64 as i64;
     let left = 0xcc00ccffi64;
     let right = 0xf0aaf0aai64;
     assert_eq!((left, right), split_key(key, 64));
@@ -569,6 +569,6 @@ fn final_pair_is_generated() {
 fn final_permutation_is_85E813540F0AB405_from_43423234_and_A4CD995() {
     let L16 = 0x43423234;
     let R16 = 0xA4CD995;
-    let permutation = 0x85E813540F0AB405;
+    let permutation = 0x85E813540F0AB405_u64 as i64;
     assert_eq!(permutation, last_permutation_with_ip_table((L16, R16)));
 }