Update Grpc.Core dependency to 2.25.0, bump package version to 2.25.0 (#644)

* Update Grpc.Core dependency to 2.25.0

* Update version.props

Author: jtattermusch

build/dependencies.props

@@ -4,7 +4,7 @@
     <CommandLineParserPackageVersion>2.3.0</CommandLineParserPackageVersion>
     <GoogleProtobufPackageVersion>3.10.0</GoogleProtobufPackageVersion>
     <GrpcDotNetPackageVersion>2.24.0</GrpcDotNetPackageVersion>
-    <GrpcPackageVersion>2.25.0-pre1</GrpcPackageVersion>
+    <GrpcPackageVersion>2.25.0</GrpcPackageVersion>
     <MicrosoftAspNetCorePackageVersion>3.0.0</MicrosoftAspNetCorePackageVersion>
     <MicrosoftBuildLocatorPackageVersion>1.2.2</MicrosoftBuildLocatorPackageVersion>
     <MicrosoftBuildPackageVersion>16.0.461</MicrosoftBuildPackageVersion>

build/version.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
 
     <!-- package version of grpc-dotnet -->
-    <GrpcDotnetVersion>2.25.0-pre1</GrpcDotnetVersion>
+    <GrpcDotnetVersion>2.25.0</GrpcDotnetVersion>
 
     <!-- assembly version of grpc-dotnet -->
     <GrpcDotnetAssemblyVersion>2.0.0.0</GrpcDotnetAssemblyVersion>