Adding -pre tag to build version to address build warning (#1010)

### Motivation and Context
New SDKs raise warnings about our SDK including prerelease dependencies
in a stable package.

_warning NU5104: A stable release of a package should not have a
prerelease dependency. Either modify the version spec of dependency
"Azure.Search.Documents [11.5.0-beta.2, )" or update the version field
in the nuspec._

### Description
Marking as "-pre" so that the builds know that we are a prerelease
package too. This will not affect the names of the builds we ship, as
those are overridden when packaging.

.github/workflows/update-version.sh

@@ -59,7 +59,7 @@ if [ -z "$buildAndRevisionNumber" ]; then
 fi
 
 propsVersionString=$(cat $propsFile | grep -i "<Version>");
-regex="<Version>([0-9.]*)<\/Version>"
+regex="<Version>([0-9.]*)-pre<\/Version>"
 if [[ $propsVersionString =~ $regex ]]; then
   propsVersion=${BASH_REMATCH[1]}
 else

dotnet/nuget/nuget-package.props

@@ -2,8 +2,10 @@
   <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <IsPackable>true</IsPackable>
-    <!-- Central version prefix - applies to all nuget packages -->
-    <Version>0.14</Version>
+    <!-- Central version prefix - applies to all nuget packages.
+         Only the numeric portion is used; '-pre' is ignored, but required 
+         for packages with prerelease dependencies -->
+    <Version>0.14-pre</Version>
   </PropertyGroup>
 
   <PropertyGroup>