fix: null_ident (#76)

## 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: #76
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>
Co-committed-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

go.mod

@@ -13,11 +13,13 @@ require (
 	github.com/hashicorp/terraform-plugin-testing v1.14.0
 	github.com/iancoleman/strcase v0.3.0
 	github.com/ivanpirog/coloredcobra v1.0.1
+	github.com/jarcoal/httpmock v1.4.1
 	github.com/joho/godotenv v1.5.1
 	github.com/ldez/go-git-cmd-wrapper/v2 v2.9.1
 	github.com/spf13/cobra v1.10.2
 	github.com/stackitcloud/stackit-sdk-go/core v0.21.1
 	github.com/stackitcloud/stackit-sdk-go/services/iaasalpha v0.1.23-alpha
+	github.com/stretchr/testify v1.11.1
 	github.com/teambition/rrule-go v1.8.2
 	gopkg.in/yaml.v3 v3.0.1
 )
@@ -33,6 +35,7 @@ require (
 	github.com/agext/levenshtein v1.2.3 // indirect
 	github.com/apparentlymart/go-textseg/v15 v15.0.0 // indirect
 	github.com/cloudflare/circl v1.6.3 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/fatih/color v1.18.0 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.1 // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
@@ -64,8 +67,8 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/oklog/run v1.2.0 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
-	github.com/stretchr/testify v1.11.1 // indirect
 	github.com/vmihailenco/msgpack v4.0.4+incompatible // indirect
 	github.com/vmihailenco/msgpack/v5 v5.4.1 // indirect
 	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect