Reduce dependabot pattern to 50 chars

a workaround for a silly error

> The property '#/updates/0/groups/otel-collector/patterns/1' was not of a maximum string length of 50

Signed-off-by: Yuri Shkuro <github@ysh.us>

.github/dependabot.yml

@@ -13,7 +13,7 @@ updates:
       otel-collector:
         patterns:
           - "go.opentelemetry.io/collector*"
-          - "github.com/open-telemetry/opentelemetry-collector-contrib/*"
+          - "github.com/open-telemetry/o*-collector-contrib/*"
       go-openapi:
         patterns:
           - "github.com/go-openapi/*"