change default input samplesheet to test one insead of fake file as n…

…f-validation now checks file existence

nextflow.config

@@ -10,7 +10,7 @@
 params {
 
     // Input options
-    input                      = "fake_input_to_build_refs.csv"
+    input                      = 'https://raw.githubusercontent.com/nf-core/test-datasets/rnafusion/testdata/human/samplesheet_valid.csv' // a valid samplesheet has to be present for parameter validation when building references
     build_references           = false
     cosmic_username            = null
     cosmic_passwd              = null