Nextflow lint results

⚠️ Warnings

Warning: modules/nf-core/plink/gwas/main.nf:33:9: Variable was declared but not used
```
    def outmeta = ""
        ^^^^^^^
```
Warning: modules/nf-core/plink/gwas/main.nf:64:9: Variable was declared but not used
```
    def args = task.ext.args ?: ''
        ^^^^
```
Warning: modules/nf-core/plink/gwas/main.nf:69:9: Variable was declared but not used
```
    def outmeta = ""
        ^^^^^^^
```
Warning: modules/nf-core/plink/vcf/main.nf:44:9: Variable was declared but not used
```
    def args = task.ext.args ?: ''
        ^^^^
```
Warning: subworkflows/local/utils_nfcore_gwas_pipeline/main.nf:32:5: Parameter was not used -- prefix with _ to suppress warning
```
    monochrome_logs   // boolean: Do not use coloured log outputs
    ^^^^^^^^^^^^^^^
```
Warning: subworkflows/local/utils_nfcore_gwas_pipeline/main.nf:35:5: Parameter was not used -- prefix with _ to suppress warning
```
    input             //  string: Path to input samplesheet
    ^^^^^
```
Warning: workflows/gwas.nf:67:26: The use of Channel to access channel factories is deprecated -- use channel instead
```
    def topic_versions = Channel.topic("versions")
                         ^^^^^^^
```