ci: update release ci.

Author: AsakusaRinne

.github/workflows/release.yml

@@ -39,7 +39,8 @@ jobs:
         $LastTag = git describe --tags;
         $DroppedTag = ($LastTag).TrimStart('v');
         echo "Last tag is: $DroppedTag";
-        $Version = $(echo $string | cut -d'-' -f1) + "-preview";
+        $Suffix = "-preview"
+        $Version = $(echo $string | cut -d'-' -f1)$Suffix;
         echo "Publishing version: $Version";
         dotnet pack ./src/TensorFlowNET.Core/Tensorflow.Binding.csproj -c Release -o packages /p:PackageVersion=$Version /p:Version=$Version;
         dotnet pack ./src/TensorFlowNET.Keras/Tensorflow.Keras.csproj -c Release -o packages /p:PackageVersion=$Version /p:Version=$Version;