pom_file generate pom.xml without project header.

I define a pom_file
```
pom_file(
name = "yak_core_pom",
targets = [
"//yakboot/yak-core",
],
template_file = "pom_template.xml",
)
```
when i build this file , it generate pom like

we expected like
```

yak-core
.......

```

anyone can help?

Reproduce the generated pom.xml from the pom_file definition using target //yakboot/yak-core and template_file "pom_template.xml". Compare the result with the expected Maven XML shown in the issue, starting at the pom_file generation entry point. Done means the generated file includes the XML declaration and project header shown in the example.

Written by the indexing model from the issue text.