Ports: Fix install actions for the bash port when re-installing the port

When re-installing the port the symlink already exists which causes
'ln -s' to fail.

Ports/bash/package.sh

@@ -17,5 +17,5 @@ build() {
 
 post_install() {
     mkdir -p "${SERENITY_BUILD_DIR}/Root/bin"
-    ln -s /usr/local/bin/bash "${SERENITY_BUILD_DIR}/Root/bin/bash"
+    ln -sf /usr/local/bin/bash "${SERENITY_BUILD_DIR}/Root/bin/bash"
 }