Fix fluentd yum repo

Dockerfile.fluentbit

@@ -1,7 +1,7 @@
 ARG REGISTRY
 FROM ${REGISTRY}/ubi8/ubi-minimal
 ARG VERSION
-RUN echo -e '[td-agent-bit]\nname=td-agent-bit\nbaseurl=https://packages.fluentbit.io/centos/7/$basearch' >/etc/yum.repos.d/td-agent-bit.repo && \
+RUN echo -e '[td-agent-bit]\nname=td-agent-bit\nbaseurl=https://packages.fluentbit.io/centos/$releasever/$basearch' >/etc/yum.repos.d/td-agent-bit.repo && \
     rpm --import https://packages.fluentbit.io/fluentbit.key && \
     microdnf update && \
     microdnf install td-agent-bit-$VERSION && \