Jenkinsfile: update API version matrix; set default to v1.40

- Added new entry for Docker 19.03
- Removed obsolete engine versions that reached EOL (both
  as Community Edition and Enterprise Edition)
- Set the fallback/default API version to v1.40, which
  corresponds with Docker 19.03 (current release)

Signed-off-by: Sebastiaan van Stijn <[email protected]>

Author: thaJeztah

Jenkinsfile

@@ -46,12 +46,14 @@ def getDockerVersions = { ->
 
 def getAPIVersion = { engineVersion ->
   def versionMap = [
-    '17.06': '1.30', '17.12': '1.35', '18.02': '1.36', '18.03': '1.37',
-    '18.06': '1.38', '18.09': '1.39'
+    '17.06': '1.30',
+    '18.03': '1.37',
+    '18.09': '1.39',
+    '19.03': '1.40'
   ]
   def result = versionMap[engineVersion.substring(0, 5)]
   if (!result) {
-    return '1.39'
+    return '1.40'
   }
   return result
 }