cr crashes as package version gets accidentially encoded

Packet versions follow semantic versioning, which allows adding build metadata to have versions like this: `3.11627+2e5eff15bf01`

cr uses the name and the version to create files like this: `cloudbees-core-3.11627+2e5eff15bf01.tgz`

Then, in [releaser.go](https://github.com/helm/chart-releaser/blob/main/pkg/releaser/releaser.go#L186) it calls `downloadURL.String()` which will give the *encoded* representation like this: `cloudbees-core-3.11627%2B2e5eff15bf01.tgz`

Therefore the file will not be found and cr crashes.

Please stick with the unencoded filename there to avoid this.