.gitignore: cleanup

Remove the entry for fuzz-fuzz.zip which lives in a directory
that no longer exists.

Add a trailing slash to directories.

Change-Id: I23e0649a2326bc995f3bda41202b73270a1df4fc
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/221024
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/.gitignore b/.gitignore
index d559d39..698e891 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,7 @@
-/.cache
-/.gocache
-/bin
-/vendor
-/internal/fuzz/wire/fuzz-fuzz.zip
+/.cache/
+/.gocache/
+/bin/
+/vendor/
 
 # This file includes artifacts of the system test that should not be checked in.
 # For files created by specific development environment (e.g. editor),