selftests: tc-testing: remove spurious './' from Makefile

Patchwork CI didn't like the extra './', so remove it.
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20231129222424.910148-3-pctammela@mojatatu.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/tc-testing/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
-TEST_PROGS += ./tdc.sh
+TEST_PROGS += tdc.sh
 TEST_FILES := action-ebpf tdc*.py Tdc*.py plugins plugin-lib tc-tests scripts
 
 include ../lib.mk