fix(ci): build the web apps once before the two backend architectures; release 0.3.1 [CI]

backend/Directory.Build.props

@@ -13,7 +13,7 @@
     <UseArtifactsOutput>true</UseArtifactsOutput>
     <ArtifactsPath>$(MSBuildThisFileDirectory)artifacts</ArtifactsPath>
     <Deterministic>true</Deterministic>
-    <Version>0.3.0</Version>
+    <Version>0.3.1</Version>
     <NuGetAudit>false</NuGetAudit>
   </PropertyGroup>
   <ItemGroup>