Fix Kokoro presubmit checks

A recent update to Kokoro broke SwiftShader's presubmit checks.
This CL attempts to fix this issue.

Bug: b/262232104
Change-Id: I7d215308321190e603c0daae736d77b2c927fba4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/70288
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
diff --git a/tests/presubmit.sh b/tests/presubmit.sh
index 10ccf53..38af885 100755
--- a/tests/presubmit.sh
+++ b/tests/presubmit.sh
@@ -8,6 +8,8 @@
 CLANG_FORMAT=${CLANG_FORMAT:-clang-format}
 GOFMT=${GOFMT:-gofmt}
 
+git config --global --add safe.directory '*'
+
 if test -t 1; then
   ncolors=$(tput colors)
   if test -n "$ncolors" && test $ncolors -ge 8; then