Bump github.com/gosimple/slug from 1.14.0 to 1.15.0 in /backend

Bumps [github.com/gosimple/slug](https://github.com/gosimple/slug) from 1.14.0 to 1.15.0.
- [Release notes](https://github.com/gosimple/slug/releases)
- [Commits](gosimple/slug@v1.14.0...v1.15.0)

---
updated-dependencies:
- dependency-name: github.com/gosimple/slug
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

backend/go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/gin-contrib/zap v1.1.4
 	github.com/gin-gonic/gin v1.10.0
 	github.com/gorilla/sessions v1.4.0
-	github.com/gosimple/slug v1.14.0
+	github.com/gosimple/slug v1.15.0
 	github.com/knadh/koanf/parsers/yaml v0.1.0
 	github.com/knadh/koanf/providers/env v1.0.0
 	github.com/knadh/koanf/providers/file v1.1.2

backend/go.sum

@@ -84,8 +84,8 @@ github.com/gorilla/securecookie v1.1.2 h1:YCIWL56dvtr73r6715mJs5ZvhtnY73hBvEF8kX
 github.com/gorilla/securecookie v1.1.2/go.mod h1:NfCASbcHqRSY+3a8tlWJwsQap2VX5pwzwo4h3eOamfo=
 github.com/gorilla/sessions v1.4.0 h1:kpIYOp/oi6MG/p5PgxApU8srsSw9tuFbt46Lt7auzqQ=
 github.com/gorilla/sessions v1.4.0/go.mod h1:FLWm50oby91+hl7p/wRxDth9bWSuk0qVL2emc7lT5ik=
-github.com/gosimple/slug v1.14.0 h1:RtTL/71mJNDfpUbCOmnf/XFkzKRtD6wL6Uy+3akm4Es=
-github.com/gosimple/slug v1.14.0/go.mod h1:UiRaFH+GEilHstLUmcBgWcI42viBN7mAb818JrYOeFQ=
+github.com/gosimple/slug v1.15.0 h1:wRZHsRrRcs6b0XnxMUBM6WK1U1Vg5B0R7VkIf1Xzobo=
+github.com/gosimple/slug v1.15.0/go.mod h1:UiRaFH+GEilHstLUmcBgWcI42viBN7mAb818JrYOeFQ=
 github.com/gosimple/unidecode v1.0.1 h1:hZzFTMMqSswvf0LBJZCZgThIZrpDHFXux9KeGmn6T/o=
 github.com/gosimple/unidecode v1.0.1/go.mod h1:CP0Cr1Y1kogOtx0bJblKzsVWrqYaqfNOnHzpgWw4Awc=
 github.com/imdario/mergo v0.3.16 h1:wwQJbIsHYGMUyLSPrEq1CT16AhnhNJQ51+4fdHUnCl4=