Nightly build seems to fail

### STARTED dist:pack 15:00:06Z

Already have image (with digest): gcr.io/github-actions-images/action-runner:latest
Unable to find image 'mcr.microsoft.com/dotnet/core/sdk:2.2' locally
2.2: Pulling from dotnet/core/sdk
Digest: sha256:3bbfbc6a7ea235322f3af249141e88b20ba06f06d07b5bda92a903bbc2dd7023
Status: Downloaded newer image for mcr.microsoft.com/dotnet/core/sdk:2.2
GITHUB_EVENT_PATH=/github/workflow/event.json
GITHUB_WORKFLOW=everyday
GITHUB_ACTION=dist:pack
GITHUB_REPOSITORY=planetarium/libplanet
GITHUB_WORKSPACE=/github/workspace
GITHUB_SHA=40ba2c2a6b49b07df81635c84ae4e06cc8cc9345
GITHUB_ACTOR=dahlia
GITHUB_EVENT_NAME=schedule

Welcome to .NET Core!
---------------------
Learn more about .NET Core: https://aka.ms/dotnet-docs
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli-docs

Telemetry
---------
The .NET Core tools collect usage data in order to help us improve your experience. The data is anonymous and doesn't include command-line arguments. The data is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.

Read more about .NET Core CLI Tools telemetry: https://aka.ms/dotnet-cli-telemetry

ASP.NET Core
------------
Successfully installed the ASP.NET Core HTTPS Development Certificate.
To trust the certificate run 'dotnet dev-certs https --trust' (Windows and macOS only). For establishing trust on other platforms refer to the platform specific documentation.
For more information on configuring HTTPS see https://go.microsoft.com/fwlink/?linkid=848054.
Microsoft (R) Build Engine version 16.1.76+g14b0a930a7 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

/usr/share/dotnet/sdk/2.2.300/NuGet.targets(121,5): error : '1.0.0-nightly.20190527+' is not a valid version string. [/github/workspace/Libplanet.sln]
/usr/share/dotnet/sdk/2.2.300/NuGet.targets(121,5): error : Parameter name: value [/github/workspace/Libplanet.sln]

Build FAILED.

/usr/share/dotnet/sdk/2.2.300/NuGet.targets(121,5): error : '1.0.0-nightly.20190527+' is not a valid version string. [/github/workspace/Libplanet.sln]
/usr/share/dotnet/sdk/2.2.300/NuGet.targets(121,5): error : Parameter name: value [/github/workspace/Libplanet.sln]
    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:02.19

### FAILED dist:pack 15:00:18Z (11.153s)
https://github.com/planetarium/libplanet/runs/136658987
planetarium / libplanet

Nightly build seems to fail #262
