adding semconv dependency to packages that use it (#156)

semconv was previously a dependency of the API, but that was recently removed

Author: brettmc

composer.json

@@ -11,6 +11,7 @@
     "php": "^8.0",
     "ext-opentelemetry": "*",
     "open-telemetry/api": "^1",
+    "open-telemetry/sem-conv": "^1",
     "symfony/http-kernel": "*",
     "symfony/http-client-contracts": "*"
   },