ICU-20503 Add Python 3 to the CI build bot path and bump Python installer to 3.7.2
diff --git a/.ci-builds/.azure-pipelines.yml b/.ci-builds/.azure-pipelines.yml
index e73c85a..b261e33 100644
--- a/.ci-builds/.azure-pipelines.yml
+++ b/.ci-builds/.azure-pipelines.yml
@@ -94,10 +94,13 @@
       - visualstudio
       - Cmd
   steps:
-    - powershell: 'Invoke-WebRequest https://www.python.org/ftp/python/3.7.1/python-3.7.1-amd64-webinstall.exe -OutFile c:\py3-setup.exe'
+    - powershell: 'Invoke-WebRequest https://www.python.org/ftp/python/3.7.2/python-3.7.2-amd64-webinstall.exe -OutFile c:\py3-setup.exe'
     - script: |
         c:\py3-setup.exe /quiet PrependPath=1 InstallAllUsers=1 Include_launcher=1 InstallLauncherAllUsers=1 Include_test=0 Include_doc=0 Include_dev=0 Include_debug=0 Include_tcltk=0 TargetDir=c:\py3
     - script: |
+        @echo ##vso[task.prependpath]C:\py3
+        @echo ##vso[task.prependpath]C:\py3\Scripts
+    - script: |
         python --version
         py -3 --version
     - task: VSBuild@1