Specify utf-8 encoding when writing a file in router.py

[Nixellion]

Without specifying "utf-8" encoding when writing a file the script fails to write text to a file in many cases.

I can't say if it's specific to OS region\language or contents of the file, but this simple change fixes any such issues, tested locally.

Changes in this PR

Add encoding="utf-8" to the file open on write.

cc/ @klen

[Nixellion]

A note, same change required for the

def read(self, name):
        """Read migration from file."""

but it's missing from this PR. I can create another PR with that change if needed

[Nixellion]

Until this PR is implemented a patch can be applied like this, in your own code, by subclassing the Router class:

from peewee_migrate import Router as BadRouter
from peewee_migrate.router import void
from peewee_migrate.template import TEMPLATE

class Router(BadRouter):
    def compile(self, name, migrate="", rollback="", num=None) -> str:  # noqa: A003
        """Create a migration."""
        if num is None:
            num = len(self.todo)

        name = "{:03}_".format(num + 1) + name
        filename = name + ".py"
        path = self.migrate_dir / filename
        with path.open("w", encoding="utf-8") as f:
            f.write(TEMPLATE.format(migrate=migrate, rollback=rollback, name=filename))

        return name
    
    def read(self, name):
        """Read migration from file."""
        path = self.migrate_dir / (name + ".py")
        with path.open("r", encoding="utf-8") as f:
            code = f.read()
            scope = {}
            code = compile(code, "<string>", "exec", dont_inherit=True)
            exec(code, scope, None)
            return scope.get("migrate", void), scope.get("rollback", void)