No package libgdiplus available
或者是
System.TypeInitializationException: The type initializer for 'Gdip' threw an exception.
> System.DllNotFoundException: Unable to load shared library 'libgdiplus' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: liblibgdiplus: cannot open shared object file: No such file or directory
at System.Drawing.SafeNativeMethods.Gdip.GdiplusStartup(IntPtr& token, StartupInput& input, StartupOutput& output)
at System.Drawing.SafeNativeMethods.Gdip..cctor()
--- End of inner exception stack trace ---
系统环境CentOS7，用的是.net 5.0编译的服务包，调用System.Drawing.Graphics生成验证码图片报错内容，经过一番折腾后解决了，
方法如下(顺序执行)：
如果在执行sudo yum install libgdiplus时报错提示：No package libgdiplus available.那就先执行安装epel命令
yum install epel-release
epel安装完成之后，再重新安装
sudo yum install libgdiplus
接着
sudo ln -s /usr/lib/libgdiplus.so /usr/lib/gdiplus.dll（32位系统）
sudo ln -s /usr/lib64/libgdiplus.so /usr/lib64/gdiplus.dll（64位系统）
重启服务，即可
