fix: fix releaser to use correct string format in gpg strings (#22)

## Description

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relates to #1234

## Checklist

- [ ] Issue was linked above
- [ ] Code format was applied: `make fmt`
- [ ] Examples were added / adjusted (see `examples/` directory)
- [x] Docs are up-to-date: `make generate-docs` (will be checked by CI)
- [ ] Unit tests got implemented or updated
- [ ] Acceptance tests got implemented or updated (see e.g. [here](f5f99d1709/stackit/internal/services/dns/dns_acc_test.go))
- [x] Unit tests are passing: `make test` (will be checked by CI)
- [x] No linter issues: `make lint` (will be checked by CI)

Reviewed-on: #22
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>
Co-committed-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

cmd/cmd/publish/gpg.go

@@ -2,19 +2,13 @@ package publish
 
 import (
 	"fmt"
+	"strings"
 )
 
 func (p *Provider) ReadGpgFile() (string, error) {
-	// Get contents of GPG key
 	gpgFile, err := ReadFile(p.GpgPubKeyFile)
 	if err != nil {
 		return "", fmt.Errorf("error reading '%s' file: %w", p.GpgPubKeyFile, err)
 	}
-
-	// loop through every line and stick with \\n
-	gpgAsciiPub := ""
-	for _, line := range gpgFile {
-		gpgAsciiPub = gpgAsciiPub + line + "\\n"
-	}
-	return gpgAsciiPub, nil
+	return strings.Join(gpgFile, "\n"), nil
 }