fix(deps): update module github.com/lestrrat-go/jwx/v3 to v4 (#297)

This PR contains the following updates:

| Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
| [github.com/lestrrat-go/jwx/v3](https://github.com/lestrrat-go/jwx) | `v3.1.0` → `v4.0.0` | ![age](https://developer.mend.io/api/mc/badges/age/go/github.com%2flestrrat-go%2fjwx%2fv3/v4.0.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/go/github.com%2flestrrat-go%2fjwx%2fv3/v3.1.0/v4.0.0?slim=true) |

---

### Release Notes

<details>
<summary>lestrrat-go/jwx (github.com/lestrrat-go/jwx/v3)</summary>

### [`v4.0.0`](https://github.com/lestrrat-go/jwx/releases/tag/v4.0.0)

[Compare Source](https://github.com/lestrrat-go/jwx/compare/v3.1.0...v4.0.0)

# Changes

v4 has many incompatibilities with v3. To see the full list of differences between
v3 and v4, please read the [Changes-v4.md file](./Changes-v4.md). Coding Agents should read [MIGRATION-v4.md](./MICRATION-v4.md)

v4.0.0 - 19 Apr 2026

- Initial v4 release. Major features:
  - Lighter: Core / Companion module separation. Less dependencies in core.
  - Faster: Use of generics and other optimizations make v4 2x\~3x faster than before.
  - Quantum-Ready: ML-KEM and ML-DSA, HPKE (+Hybrid) are supported through companion modules.
- See Changes-v4.md for a full set of Changes since v3.

</details>

---

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---------

Co-authored-by: Joakim Olsson <joakim@unbound.se>
Reviewed-on: #297
Co-authored-by: Renovate Bot <renovate@unbound.se>
Co-committed-by: Renovate Bot <renovate@unbound.se>

auth/jwt.go

@@ -8,10 +8,10 @@ import (
 	"time"
 
 	"github.com/google/uuid"
-	"github.com/lestrrat-go/jwx/v3/jwa"
-	"github.com/lestrrat-go/jwx/v3/jwk"
-	"github.com/lestrrat-go/jwx/v3/jws"
-	"github.com/lestrrat-go/jwx/v3/jwt"
+	"github.com/lestrrat-go/jwx/v4/jwa"
+	"github.com/lestrrat-go/jwx/v4/jwk"
+	"github.com/lestrrat-go/jwx/v4/jws"
+	"github.com/lestrrat-go/jwx/v4/jwt"
 )
 
 const (
@@ -38,7 +38,7 @@ func NewJWTService(issuer, audience, adminClaim, emailClaim string) (*JWTService
 	}
 
 	// Create JWK from private key
-	key, err := jwk.Import(privateKey)
+	key, err := jwk.Import[jwk.Key](privateKey)
 	if err != nil {
 		return nil, fmt.Errorf("create JWK from private key: %w", err)
 	}
@@ -98,7 +98,7 @@ func (s *JWTService) SignToken(claims map[string]interface{}) (string, error) {
 	}
 
 	// Create JWK from private key for signing
-	key, err := jwk.Import(s.privateKey)
+	key, err := jwk.Import[jwk.Key](s.privateKey)
 	if err != nil {
 		return "", fmt.Errorf("create signing key: %w", err)
 	}