Update fws using Ubuntu 20.10 EOL to 21.10 (#7097)

* [symfony] Fix and update to php 8.1

* [symfony] Update to v6

* Update fws using ubuntu 20.10 EOL to 21.10

* Update fws using ubuntu 20.10 EOL to 21.10

frameworks/C/lwan/lwan-lua.dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:20.10
+FROM ubuntu:21.10
 
 RUN apt-get update -yqq && \
 	apt-get install -yqq \

frameworks/C/lwan/lwan.dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:20.10
+FROM ubuntu:21.10
 
 RUN apt-get update -yqq && \
 	apt-get install -yqq \

frameworks/C/nginx/nginx.dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:20.10
+FROM ubuntu:21.10
 
 ARG DEBIAN_FRONTEND=noninteractive