refactor: add static statement

Author: vbetsch

src/main/java/io/github/vbetsch/codecracker/CodeCracker.java

@@ -3,16 +3,16 @@
 import java.util.Map;
 
 public class CodeCracker {
-    private final Map<Character, Character> translations = Map.of(
+    private static final Map<Character, Character> translations = Map.of(
             'a', '!',
             'b', ')'
     );
 
-    public char decryptLetter(char letter) {
-        return this.translations.get(letter);
+    public static char decryptLetter(char letter) {
+        return translations.get(letter);
     }
 
-    public String decryptWord(String string) {
+    public static String decryptWord(String string) {
         StringBuilder stringBuilder = new StringBuilder();
         for (char c : string.toCharArray()) {
             stringBuilder.append(decryptLetter(c));