manibuilder: Replace `master` branch with `main`

Change-Id: I4a7c6d0238cf915473cd5a2143e6afc00817caac
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/73431
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/util/manibuilder/Makefile b/util/manibuilder/Makefile
index a30d08d..e6834cf 100644
--- a/util/manibuilder/Makefile
+++ b/util/manibuilder/Makefile
@@ -49,7 +49,7 @@
 $(ALL_TAGS): export TEST_REMOTE?=$(if $(TEST_LOCAL),\
 					git://mani-git/flashrom.git,\
 					origin)
-$(ALL_TAGS): export TEST_REVISION?=$(if $(TEST_LOCAL),HEAD,master)
+$(ALL_TAGS): export TEST_REVISION?=$(if $(TEST_LOCAL),HEAD,main)
 $(ALL_TAGS): %: %-check-build mani-net $(if $(TEST_LOCAL),local-git)
 	$(QUIET_TEST)docker rm -f mani_$(call ident,$*) >/dev/null 2>&1 || true
 	$(QUIET_TEST)\