install-prereq: Specify flatbuffers python version explicitly

Assign a version for the flatbuffers python installed from the local repo
with a value that is agreed with tensorflow. This local python module
might not actually work with the full tensorflow 2 functionality, but it
works for the ML work this project cares about (TFLite -> TOSA HLO)

Change-Id: I9d4afd4addbc6910014a8b431cfc59e367ed441d

install-prereqs.sh

diff --git a/install-prereqs.sh b/install-prereqs.sh
index 9dd39fd..81e9073 100755
--- a/install-prereqs.sh
+++ b/install-prereqs.sh
@@ -140,8 +140,11 @@
         for REQ_FILE in ${PYTHON_REQUIREMENTS} ; do
             PIP_INSTALL_ARGS+=("-r" "${REQ_FILE}")
         done
-        PIP_INSTALL_ARGS+=("${ROOTDIR}/sw/flatbuffers/python")
         pip3 install "${PIP_INSTALL_ARGS[@]}"
+        # Install flatbuffer from local source
+        # Note: Specify a version based on a fixed timestamp so tensorflow
+        # module won't complain about it (>=23.1.21).
+        VERSION=v20230510 pip3 install "${ROOTDIR}/sw/flatbuffers/python"
     fi
 }