ci: execute test scripts via sh

Cabal 3.4 strips the execute permission from extra source files;
see haskell/cabal#6666.  This impacts our
test scripts and causes CI to fail.

Execute test scripts via sh(1) to avoid test failure due to no
execute permission.

Author: frasertweedale

Tests/allTests.sh

@@ -9,7 +9,7 @@ fi
 for TESTDIR in `find . -mindepth 1 -type d`; do
     echo "Running $TESTDIR"
     cd $TESTDIR
-    TEST_RESULT=`./runTest.sh 2>&1`
+    TEST_RESULT=`sh ./runTest.sh 2>&1`
     TEST_STATUS=$?
     if [ "$TEST_STATUS" -ne 0 ]; then
         echo "$TESTDIR failed; output:"