Update PTB version in cookie cutter template

[ckunki]

Currently, ptb/project-template/{{cookiecutter.repo_name}}/pyproject.toml contains

[tool.poetry.group.dev.dependencies]
exasol-toolbox = "^1.6.0"

This should at least be

[tool.poetry.group.dev.dependencies]
exasol-toolbox = ">=4.01, <5"

But I think the release process of the PTB should include checking or even updating this.