Move flatbuffers from local to pypi

We don't have vendored flatbuffers in the manifest anymore. For TBM,
download the flatbuffer module from pypi

Change-Id: I04151ee71d1a1165cf6094c749098b9004da473d

install-prereqs.sh

diff --git a/install-prereqs.sh b/install-prereqs.sh
index c8c7793..0018139 100755
--- a/install-prereqs.sh
+++ b/install-prereqs.sh
@@ -145,12 +145,6 @@
             PIP_INSTALL_ARGS+=("-r" "${REQ_FILE}")
         done
         pip3 install "${PIP_INSTALL_ARGS[@]}"
-        if [[ -d "${ROOTDIR}/sw/flatbuffers/python" ]]; then
-            # Install flatbuffer from local source
-            # Note: Specify a version based on a fixed timestamp so tensorflow
-            # module won't complain about it (>=23.1.21).
-            VERSION=v20230510 pip3 install "${ROOTDIR}/sw/flatbuffers/python"
-        fi
     fi
 }
 

python-requirements.txt

diff --git a/python-requirements.txt b/python-requirements.txt
index 5165693..e1f095a 100644
--- a/python-requirements.txt
+++ b/python-requirements.txt
@@ -22,6 +22,9 @@
 
 # camkes-deps
 
+# Flatbuffers for TBM trace data
+flatbuffers==23.5.26
+
 hjson
 jsonschema
 lit