ci: allow the full Alpha string in the build matrix

Author: nschonni

genMatrix.js

@@ -52,7 +52,7 @@ const getAffectedDockerfiles = (filesAdded, filesModified, filesRenamed) => {
 };
 
 const getFullNodeVersionFromDockerfile = (file) =>
-  fs.readFileSync(file, 'utf8').match(/^ENV NODE_VERSION=(\d*\.*\d*\.\d*)/m)[1];
+  fs.readFileSync(file, 'utf8').match(/^ENV NODE_VERSION=(\S*)/m)[1];
 
 const getDockerfileMatrixEntry = (file) => {
   const [variant] = path.dirname(file).split(path.sep).slice(-1);