Use PSDocs v0.9.0 release (#8)

Author: BernieWhite

Dockerfile

@@ -1,15 +1,13 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
 
-ARG MODULE_VERSION=0.9.0-B2107020
-
-# NOTE: Use pre-release version with -MinimumVersion -AllowPrerelease.
+ARG MODULE_VERSION=0.9.0
 
 FROM mcr.microsoft.com/powershell:7.1.3-alpine-3.12-20210616
 SHELL ["pwsh", "-Command"]
 RUN $ProgressPreference = [System.Management.Automation.ActionPreference]::SilentlyContinue; \
     $Null = New-Item -Path /ps_modules/ -ItemType Directory -Force; \
-    Save-Module -Name PSDocs -MinimumVersion ${MODULE_VERSION} -Force -Path /ps_modules/ -AllowPrerelease;
+    Save-Module -Name PSDocs -RequiredVersion ${MODULE_VERSION} -Force -Path /ps_modules/;
 
 COPY LICENSE README.md powershell.ps1 /
 CMD ["pwsh", "-File", "/powershell.ps1"]