Improve support for FreeBSD (zaproxy#8997)

Check for FreeBSD in `Constant#isLinux()`.

Signed-off-by: Alonso Cárdenas <11150989+alonsobsd@users.noreply.github.com>

Author: alonsobsd

zap/src/main/java/org/parosproxy/paros/Constant.java

@@ -1465,7 +1465,8 @@ public static boolean isWindows() {
 
     // Determine Linux Operating System
     // ZAP: Changed to final.
-    private static final Pattern patternLinux = Pattern.compile("linux", Pattern.CASE_INSENSITIVE);
+    private static final Pattern patternLinux =
+            Pattern.compile("linux|freebsd", Pattern.CASE_INSENSITIVE);
 
     public static boolean isLinux() {
         String os_name = System.getProperty("os.name");