update pyotracker to use pyomo 6.9 as the recent release (#566)

Author: DLWoodruff

.github/workflows/pyotracker.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        pyomo-version: [6.7.1, main]
+        pyomo-version: [6.9.1, main]
     steps:
       - uses: actions/checkout@v3
       - uses: conda-incubator/setup-miniconda@v2