build(deps): bump github.com/sigstore/sigstore/pkg/signature/kms/hashivault

Bumps [github.com/sigstore/sigstore/pkg/signature/kms/hashivault](https://github.com/sigstore/sigstore) from 1.8.12 to 1.8.15.
- [Release notes](https://github.com/sigstore/sigstore/releases)
- [Commits](sigstore/sigstore@v1.8.12...v1.8.15)

---
updated-dependencies:
- dependency-name: github.com/sigstore/sigstore/pkg/signature/kms/hashivault
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

go.mod

@@ -46,7 +46,7 @@ require (
 	github.com/sigstore/sigstore/pkg/signature/kms/aws v1.8.15
 	github.com/sigstore/sigstore/pkg/signature/kms/azure v1.8.12
 	github.com/sigstore/sigstore/pkg/signature/kms/gcp v1.8.12
-	github.com/sigstore/sigstore/pkg/signature/kms/hashivault v1.8.12
+	github.com/sigstore/sigstore/pkg/signature/kms/hashivault v1.8.15
 	go.opentelemetry.io/otel v1.34.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.34.0
 	go.opentelemetry.io/otel/sdk v1.34.0
@@ -113,7 +113,7 @@ require (
 	github.com/hashicorp/go-secure-stdlib/strutil v0.1.2 // indirect
 	github.com/hashicorp/go-sockaddr v1.0.2 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
-	github.com/hashicorp/vault/api v1.15.0 // indirect
+	github.com/hashicorp/vault/api v1.16.0 // indirect
 	github.com/jellydator/ttlcache/v3 v3.3.0 // indirect
 	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/letsencrypt/boulder v0.0.0-20240620165639-de9c06129bec // indirect