Remove deprecated Mac OSX 10.14 image in ADO pipeline (colmap#1383)

Author: ahojnnes

.azure-pipelines/build.yaml

@@ -16,10 +16,6 @@ jobs:
       displayName: 'Ubuntu 20.04 (CUDA)'
       ubuntuVersion: 20.04
       cudaEnabled: true
-  - template: build-mac.yaml
-    parameters:
-      displayName: 'Mac 10.14'
-      macVersion: 10.14
   - template: build-mac.yaml
     parameters:
       displayName: 'Mac 10.15'