update expression

Author: Gareth Emslie

azure-pipelines.yaml

@@ -7,7 +7,7 @@ variables:
   MinorVersion : 0
   PatchVersion : $[counter(format('nexus-extension-{0}.{1}.{2}',variables['Build.SourceBranchName'],variables['MajorVersion'],variables['MinorVersion']), 156)]
   isPR : $[startsWith(variables['Build.SourceBranch'],'refs/pull/')] 
-  isMain : $[startsWith(variables['Build.SourceBranch'],'refs/heads/main')] 
+  isMain : $[startsWith(variables['Build.SourceBranch'],'refs/heads/master')] 
 stages:
   - stage : build_package
     displayName: Build & Package Extension