chore: Upgrade Flux to 2.6.4 (#5132)

Author: weave-gitops-bot

Makefile

@@ -7,7 +7,7 @@ BUILD_TIME?=$(shell date +'%Y-%m-%d_%T')
 BRANCH?=$(shell which git > /dev/null && git rev-parse --abbrev-ref HEAD)
 GIT_COMMIT?=$(shell which git > /dev/null && git log -n1 --pretty='%h')
 VERSION?=$(shell which git > /dev/null && git describe --always --match "v*")
-FLUX_VERSION=2.6.3
+FLUX_VERSION=2.6.4
 CHART_VERSION=$(shell which yq > /dev/null && yq e '.version' charts/gitops-server/Chart.yaml)
 TIER=oss