Bump ubuntu to 20.04

Your Name · Your Name · commit 502295769e91 · 2021-03-04T17:40:02.000Z
diff --git a/Dockerfile b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:18.04
+FROM ubuntu:20.04
 
 RUN sed -i s/^deb-src.*// /etc/apt/sources.list
 

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-FROM ubuntu:18.04`
	`1`	`+FROM ubuntu:20.04`
`2`	`2`
`3`	`3`	`RUN sed -i s/^deb-src.*// /etc/apt/sources.list`
`4`	`4`