Set Gerrit to 3.7.0-rc0

Also upgrade AlmaLinux to 8.6

Change-Id: I6aa378b12b174b58211a8a829f4bbb556b39f2cd
diff --git a/almalinux/8/Dockerfile b/almalinux/8/Dockerfile
index 7638583..8baf849 100644
--- a/almalinux/8/Dockerfile
+++ b/almalinux/8/Dockerfile
@@ -1,4 +1,4 @@
-FROM almalinux:8.5
+FROM almalinux:8.6
 MAINTAINER Gerrit Code Review Community
 
 # Add Gerrit packages repository
@@ -10,7 +10,7 @@
 # (pre-trans Gerrit script needs to have access to the Java command)
 RUN yum -y install initscripts && \
     yum -y install java-11-openjdk && \
-    yum -y install gerrit-3.6.1-1 && \
+    yum -y install gerrit-3.7.0-0rc0 && \
     /entrypoint.sh init && \
     rm -f /var/gerrit/etc/{ssh,secure}* && rm -Rf /var/gerrit/{static,index,logs,data,index,cache,git,db,tmp}/* && chown -R gerrit:gerrit /var/gerrit && \
     yum -y clean all
diff --git a/ubuntu/20/Dockerfile b/ubuntu/20/Dockerfile
index 5899dcb..3df2ddf 100644
--- a/ubuntu/20/Dockerfile
+++ b/ubuntu/20/Dockerfile
@@ -16,7 +16,7 @@
 # Install OpenJDK and Gerrit in two subsequent transactions
 # (pre-trans Gerrit script needs to have access to the Java command)
 RUN apt-get -y install openjdk-11-jdk
-RUN apt-get -y install gerrit=3.6.1-1 && \
+RUN apt-get -y install gerrit=3.7.0-0rc0 && \
     apt-mark hold gerrit && \
     /entrypoint.sh init && \
     bash -c 'rm -f /var/gerrit/etc/{ssh,secure}* && rm -Rf /var/gerrit/{static,index,logs,data,index,cache,git,db,tmp}/*' && \