t5310: drop lib-bundle.sh include

Commit ddfe900612 (test-lib-functions: move function to lib-bitmap.sh,
2021-02-09) meant to include lib-bitmap.sh in t5310, but also includes
lib-bundle.sh. Yet we don't use any of its functions, nor have anything
to do with bundles. This is probably just a typo/copy-paste error, as
lib-bundle.sh was added (correctly) to other scripts in the same series.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index 40b9f63..4703ec3 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -5,7 +5,6 @@
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
-. "$TEST_DIRECTORY"/lib-bundle.sh
 . "$TEST_DIRECTORY"/lib-bitmap.sh
 
 objpath () {