Move EXPECT_PASSED_TESTS from GH Actions config to Makefile

That way manual test invocation will still know about the target number of
passed tests

Author: sio

.github/workflows/test.yml

@@ -8,7 +8,6 @@ jobs:
   pqnet:
     runs-on: windows-latest
     env:
-      EXPECT_PASSED_TESTS: 30
       PQ: 'C:\Program Files\PowerQueryNet\PQNet.exe'
     steps:
       - uses: actions/checkout@v1

CI/Makefile

@@ -2,6 +2,9 @@ PQ?=pqnet
 PY?=python3
 
 
+export EXPECT_PASSED_TESTS=30
+
+
 export LIBPQ=$(abspath ../)
 TEST_RESULTS=results.json