Bump version to 1.4.0-dev #789

Job	Run time
cache-env	1s
🧪 Unit tests	2m 53s
⚙️ Static checks	8s
🍎 macOS / Editor (x86_64, release)	2m 52s
🪟 Windows / Editor (x86_64, release)	18m 33s
🍎 macOS / Editor (arm64, release)	3m 5s
🐧 Linux / Editor (x86_64, release)	14m 16s
🔌 GDExtension / 🐧 Linux (x86_64, release)	25s
🐧 Linux / Template (x86_64, release)	9m 6s
🔌 GDExtension / 🐧 Linux (x86_64, debug)	26s
🔌 GDExtension / 🪟 Windows (x86_64, release)	2m 37s
🔌 GDExtension / 🪟 Windows (x86_64, debug)	4m 28s
🐧 Linux / Editor .NET (x86_64, release)	16m 10s
🔌 GDExtension / 🍎 macOS (universal, release)	1m 4s
🔌 GDExtension / 🍎 macOS (universal, debug)	58s
🍎 macOS / Make macOS Bundles (tmp-macos, false, true)	36s
🔌 GDExtension / 📦 Package extension	28s
🪟 Windows / .NET assembly for ${{ matrix.opts.arch }}	0s
	1h 18m 6s

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