Remove Pharo64-12 from test matrix

Only keep Pharo 13 and Pharo 14 in the CI. Add a <expectedFailure> for one failing test until we fix the issue.

Author: SergeStinckwich

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
       PROJECT_NAME: MathVectorMatrix-${{ matrix.smalltalk }}
     strategy:
       matrix:
-        smalltalk: [Pharo64-12, Pharo64-13, Pharo64-14]
+        smalltalk: [Pharo64-13, Pharo64-14]
     name: ${{ matrix.smalltalk }}
     steps:
       - uses: actions/checkout@v3