refactoring: replaced 1 with true

src/userinput.c

@@ -122,7 +122,7 @@ char *gets(char *message, unsigned long *minLength, unsigned long *maxLength) {
 }
 
 long double getNumber(char *message, long double *min, long double *max, long double *greaterThan, long double *smallerThan, long double leftBorder, long double rightBorder) {
-    while (1) {
+    while (true) {
         char *input = gets(message, NULL, NULL);
         if (strlen(input) == 0) {
             printText("Fehlende Eingabe!\n");