I am going to create automatic deploy to my testing server via SSH in Github Actions. I was created connecting by private key. It's work correctly on local (tested in ubuntu:latest docker image), but when I push my code into repository I got error.

Run ssh -i ~/.ssh/private.key -o "StrictHostKeyChecking no" ***@*** -p *** whoami
Warning: Permanently added '[***]:***' (ED25519) to the list of known hosts.
Load key "/home/runner/.ssh/private.key": error in libcrypto
Permission denied, please try again.
Permission denied, please try again.
***@***: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Error: Process completed with exit code 255.

My workflow code:

name: Testing deploy
on:
  push:
    branches:
      - develop
      - feature/develop-autodeploy
jobs:
  build:
    name: Build and deploy
    runs-on: ubuntu-latest
    steps:
      - run: mkdir -p ~/.ssh/
      - run: echo "{{ secrets.STAGING_KEY }}" > ~/.ssh/private.key
      - run: chmod 600 ~/.ssh/private.key
      - run: ssh -i ~/.ssh/private.key -o "StrictHostKeyChecking no" ${{ secrets.STAGING_USER }}@${{ secrets.STAGING_HOST }} -p ${{ secrets.STAGING_PORT }} whoami

I was tried 3rd-hand packages e.g. D3rHase/ssh-command-action and appleboy/ssh-action with another errors.