Update nf-validation to nf-schema

Use fixed version to prevent plugin check every time we run the pipeline (in particular when running tests)

pipelines/nextflow/workflows/nextflow.config

@@ -20,9 +20,8 @@ nextflowVersion = '!>=23.01'
 NXF_WORK = System.getenv("NXF_WORK") ?: "$PWD/work"
 ENSEMBL_ROOT_DIR = System.getenv("ENSEMBL_ROOT_DIR") ?: "$PWD"
 
-plugins {
-    id 'nf-validation'
-}
+
+plugins { id '[email protected]' }
 
 params {
     help = false