Fix GitHub actions command injection

[dumitory-dev]

Description

Fix GitHub actions command injection
In the file telegram-bot.yml lines:

        elif [[ ! -z "${{ github.event.workflow_run }}" && "${{ github.event.workflow_run.conclusion }}" == "success" ]]; then
          TEXT=`echo -e "<a href=\"${{ env.UNIVERSUM_LOG }}\">Universum run for branch '${{ env.UNIVERSUM_BRANCH }}'</a> <b>SUCCEDED</b>; commit ${{ env.UNIVERUM_COMMIT }} "`
        elif [[ ! -z "${{ github.event.workflow_run }}" && "${{ github.event.workflow_run.conclusion }}" == "failure" ]]; then
          TEXT=`echo -e "<a href=\"${{ env.UNIVERSUM_LOG }}\">Universum run for branch '${{ env.UNIVERSUM_BRANCH }}'</a> <b>FAILED</b>; commit ${{ env.UNIVERUM_COMMIT }} "`
        fi

Can be command injection with untrusted env.UNIVERSUM_BRANCH input. See this PR for example.
An attacker can steal repo secrets that are stored in the env URL variable and maybe GITHUB_TOKEN

This PR fixes this problem with guide from official github docs