Add buster build

This is purely copy-pasta from the Stretch build.
12 jobs for add/buster in 7 minutes and 18 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #2041
lint-dockerfile

00:01:33

passed #2042
lint-shell-script

00:01:26

 
  Deploy
failed #2044
build-debian-buster-build-dev

00:01:44

passed #2046
build-debian-jessie-build-dev

00:05:43

passed #2045
build-debian-stretch-build-dev

00:03:08

passed #2043
build-golang-dev

00:01:13

passed #2052
allowed to fail
build-php-5.3-dev

00:03:29

passed #2051
allowed to fail
build-php-5.6-dev

00:04:03

passed #2050
allowed to fail
build-php-7.0-dev

00:04:11

passed #2049
build-php-7.1-dev

00:03:58

passed #2048
build-php-7.2-dev

00:04:14

passed #2047
build-php-7.3-dev

00:03:57

 
Name Stage Failure
failed
build-debian-buster-build-dev Deploy
Ign:4 https://packages.sury.org/php n/a InRelease
Get:5 http://cdn-fastly.deb.debian.org/debian buster-updates InRelease [46.8 kB]
Err:6 https://packages.sury.org/php n/a Release
404 Not Found [IP: 68.70.205.3 443]
Get:7 http://cdn-fastly.deb.debian.org/debian buster/main amd64 Packages [7977 kB]
Reading package lists...
E: The repository 'https://packages.sury.org/php n/a Release' does not have a Release file.
The command '/bin/sh -c apt-get update && apt-get -y --no-install-recommends install git dh-make build-essential autoconf autotools-dev libpcre3 libpcre3-dev libz-dev gnupg libssl-dev && apt-get clean && rm -rf /var/lib/apt/lists/*' returned a non-zero code: 100
ERROR: Job failed: exit code 100