CSHARP-3626: Pin NuGet client version in the build script (#514)

Author: MikalaiMazurenka

build.ps1

@@ -120,7 +120,7 @@ $ADDINS_DIR = Join-Path $TOOLS_DIR "Addins"
 $MODULES_DIR = Join-Path $TOOLS_DIR "Modules"
 $NUGET_EXE = Join-Path $TOOLS_DIR "nuget.exe"
 $CAKE_EXE = Join-Path $TOOLS_DIR "Cake/Cake.exe"
-$NUGET_URL = "https://dist.nuget.org/win-x86-commandline/latest/nuget.exe"
+$NUGET_URL = "https://dist.nuget.org/win-x86-commandline/v5.7.1/nuget.exe"
 $PACKAGES_CONFIG = Join-Path $TOOLS_DIR "packages.config"
 $PACKAGES_CONFIG_MD5 = Join-Path $TOOLS_DIR "packages.config.md5sum"
 $ADDINS_PACKAGES_CONFIG = Join-Path $ADDINS_DIR "packages.config"