Go back to hardcoding WDL files in CI

I couldn't get the dynamic detection to work, so go back to the
simple method.

.github/workflows/womtool.yml

@@ -20,36 +20,19 @@ concurrency:
 
 jobs:
 
-  detect-wdl-files:
-    runs-on: ubuntu-latest
-    name: "Detect WDL files"
-    outputs:
-        matrix: ${{ steps.detect-files.outputs.matrix }}
-
-    steps:
-
-      - name: Checkout Code Repository
-        uses: actions/checkout@v4
-
-      - name: Detect WDL files
-        id: detect-files
-        run: |
-          # Find the WDL files
-          wdl_files=`find . -name "*.wdl" -type f -print0 | xargs -0`
-          # Add double quotes and replace spaces with commas.
-          wdl_files=\"${wdl_files// /\",\"}\"
-
-          echo "matrix={\"wdl-file\":[$wdl_files]" >> $GITHUB_OUTPUT
-
-      - name: Show WDL files
-        run: echo "${{ steps.detect-files.outputs.matrix }}"
-
   run-womtool:
-    needs: detect-wdl-files
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
-      matrix: ${{ fromJSON(needs.detect-wdl-files.outputs.matrix) }}
+      matrix:
+        wdl-file: [
+            ./gsr_data_report.wdl,
+            ./check_vcf_samples.wdl,
+            ./pheno_qc/pheno_qc.wdl,
+            ./validate_genotype_model.wdl,
+            ./validate_gsr_model.wdl,
+            ./validate_phenotype_model.wdl,
+        ]
 
     name: "Run womtool: ${{ matrix.wdl-file }}"