Add diffutils to UBI 9

bnbarham · bnbarham · commit d2463e07abd7 · 2023-07-08T18:55:38.000-07:00
This presumably came through clang previously as a transitive
dependency. Add it directly.
diff --git a/swift-ci/master/rhel-ubi/9/Dockerfile b/swift-ci/master/rhel-ubi/9/Dockerfile
@@ -7,6 +7,7 @@ RUN yum install -y  \
   git               \
   gcc-c++           \
   cmake             \
+  diffutils         \
   make              \
   libcurl-devel     \
   libedit-devel     \
