azure-pipelines: Avoid unsupported mapping values

This ensure the syntax is correct allowing the jobs to be triggered.
The azure pipelines error was:
"This is an informational run. There was a YAML error preventing Azure
Pipelines from determining if the pipeline should run. If you expected
this pipeline to run, please validate your YAML. If it's valid, please
try again later."

Signed-off-by: Dan Nechita <dan.nechita@analog.com>

Author: dNechita

azure-pipelines.yml

@@ -5,8 +5,10 @@ variables:
   isMain: $[eq(variables['Build.SourceBranch'], 'refs/heads/main')]
   isRelease: $[startsWith(variables['Build.SourceBranch'], 'refs/tags/v')]
   # Default build type for all builds
-  cmakeBuildType: $[ if eq(variables.isRelease, true) ]: 'Release'
-                  $[ if ne(variables.isRelease, true) ]: 'RelWithDebInfo'
+  ${{ if startsWith(variables['Build.SourceBranch'], 'refs/tags/v') }}:
+    cmakeBuildType: 'Release'
+  ${{ else }}:
+    cmakeBuildType: 'RelWithDebInfo'
 
 trigger:
   branches: