build: fix text escaping for multiline with "`" commit messages

[blacha]

Motivation

There is a bug causing container builds to fail if the commit message contains a backtick "`"

When github replaces the commit message it directly inserts it into the script without any escaping

const x = ${{ github....commit_message }}

// directly replaced no quotes included, and includes \n as line breaks
const x = build: fix text.
body text here
some `comments` in the body

using toJson()

const x  = ${{ toJson(...commit_message) }}

// all escaped and includes a starting "
const x = "build: fix text.\nbody text here\nsome `comments` in the body"

using toJson and backticks

const x  = `${{ toJson(...commit_message) }}`

// Broken string
const x = `"build: fix text.\nbody text here\nsome `comments` in the body"`
//        ^                                        ^

Modifications

Removing "`" as toJson() will handle the string escaping.

Verification

Building containers as part of pull request.