docker version matrix: update Alpine version

docker/README.md

@@ -7,14 +7,14 @@
 | Ubuntu 18.04 | latest-ubuntu   | 7.9.dev    | 4.9.3 | 2.2.3 | 1.8.0 | 3.6.9  | 1.04 GB    |
 | Ubuntu 19.10 | latest-ubuntu19 | 7.9.dev    | 5.2.0 | 2.4.2 | 1.9.1 | 3.7.5  |  850 MB    |
 | Debian 10.1  | latest-debian   | 7.9.dev    | 5.2.0 | 2.4.0 | 1.8.0 | 3.7.3  | 1.14 GB    |
-| Alpine 3.11  | latest-alpine   | 7.9.dev    | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
+| Alpine 3.12  | latest-alpine   | 7.9.dev    | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
 |--------------|-----------------|------------|-------|-------|-------|--------|------------|
 | Ubuntu 18.04 | stable-ubuntu   | 7.8 branch | 4.9.3 | 2.2.3 | 1.8.0 | 3.6.9  | 1.04 GB    |
 | Ubuntu 19.10 | stable-ubuntu19 | 7.8 branch | 5.2.0 | 2.4.2 | 1.9.1 | 3.7.5  |  850 MB    |
 | Debian 10.1  | stable-debian   | 7.8 branch | 5.2.0 | 2.4.0 | 1.8.0 | 3.7.3  | 1.14 GB    |
-| Alpine 3.11  | stable-alpine   | 7.8 branch | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
+| Alpine 3.12  | stable-alpine   | 7.8 branch | 7.0.1 | 3.1.2 | 2.1.0 | 3.5.8  |  385 MB    |
 
-Last update: 25 Aug 2020 (source: https://hub.docker.com/r/mundialis/grass-py3-pdal/builds)
+Last update: 17 Sep 2020 (source: https://hub.docker.com/r/mundialis/grass-py3-pdal/builds)
 
 # Requirements