Make runtime exception for graphviz as well

.github/workflows/main.yml

@@ -231,7 +231,7 @@ jobs:
         run: |
           mkdir -p runtime
           git clone https://github.com/kaitai-io/kaitai_struct_${{matrix.tsv.target}}_runtime runtime/${{matrix.tsv.target}}
-        if: matrix.tsv.target != 'construct'
+        if: matrix.tsv.target != 'construct' && matrix.tsv.target != 'graphviz'
 
       # Two different job_id parsers: for 3 values (with subtarget being non-empty) and for 2 values (with subtarget being empty)
       - name: job_id parser 3