prereqs: Add bazel-7.1.2

bazel version is locked to 7.1.2 at
https://github.com/google/mpact-sim/blob/07b997e11d6aafeb3839f5085708907b03a98e64/.bazeliskrc
to build kelvin ISS.

Add bazel 7.1.2 to prepare kelvin ISS update
Bug: 360389557
Test: nop at this moment

Change-Id: I0dc298e89ff8425a8984e4f7098130e5443bad4e

install-prereqs.sh

diff --git a/install-prereqs.sh b/install-prereqs.sh
index 50d8451..fbdb1a2 100755
--- a/install-prereqs.sh
+++ b/install-prereqs.sh
@@ -21,6 +21,7 @@
     asciidoctor
     bazel
     bazel-6.2.1
+    bazel-7.1.2
     bison
     build-essential
     ccache