Use net8.0 SDK for build script. (#1308)

Author: sanych-sun

evergreen/evergreen.yml

@@ -2120,7 +2120,6 @@ task_groups:
     setup_group:
       - func: fetch-source
       - func: prepare-resources
-      - func: install-dotnet
       - command: subprocess.exec
         params:
           binary: bash

evergreen/install-dotnet.sh

@@ -8,10 +8,10 @@ if [[ $OS =~ [Ww]indows.* ]]; then
   echo "Downloading Windows .NET SDK installer into $DOTNET_SDK_PATH folder..."
   curl -Lfo "$DOTNET_SDK_PATH"/dotnet-install.ps1 https://dot.net/v1/dotnet-install.ps1
   echo "Installing .NET LTS SDK..."
-  powershell.exe "$DOTNET_SDK_PATH"/dotnet-install.ps1 -Channel 6.0 -InstallDir "$DOTNET_SDK_PATH" -NoPath
+  powershell.exe "$DOTNET_SDK_PATH"/dotnet-install.ps1 -Channel 8.0 -InstallDir "$DOTNET_SDK_PATH" -NoPath
 else
   echo "Downloading .NET SDK installer into $DOTNET_SDK_PATH folder..."
   curl -Lfo "$DOTNET_SDK_PATH"/dotnet-install.sh https://dot.net/v1/dotnet-install.sh
   echo "Installing .NET LTS SDK..."
-  bash "$DOTNET_SDK_PATH"/dotnet-install.sh --channel 6.0 --install-dir "$DOTNET_SDK_PATH" --no-path
+  bash "$DOTNET_SDK_PATH"/dotnet-install.sh --channel 8.0 --install-dir "$DOTNET_SDK_PATH" --no-path
 fi