[FIX] missing newline in generated files

In a proper file each line end with a newline character, even the last
one.

Wrong file:

Using `write()` function does not add a newline character at the end of
the write. So writing a string in a file with `write()` leads to a file
like this:

```
line1\n
line2\n
lastline
```

Good file:

Using the `print()` command automatically ends the string with a newline
character. So that we ends with a proper file:
```
line1\n
line2\n
lastline\n
```

Also the with statement automatically closes the file at the end of the
block.

odoo_openupgrade_wizard/tools/tools_system.py

@@ -78,8 +78,7 @@ def ensure_file_exists_from_template(
 
     with open(file_path, "w") as f:
         logger.info(log_text)
-        f.write(output)
-        f.close()
+        print(output, file=f)
 
 
 def git_aggregate(folder_path: Path, config_path: Path, jobs: int):