fix(tests): restore SCENARIO closing brace lost in upstream merge

The merge of upstream main into the PR branch resolved the conflict in
test_gcodewriter.cpp by keeping both sides but dropping the closing brace
of the set_pressure_advance BBL SCENARIO. That nested the incoming
TEST_CASE inside it and broke the build on every target that compiles the
test suite:

  test_gcodewriter.cpp:1087: error: namespaces can only be defined in
  global or namespace scope

Close the SCENARIO before the TEST_CASE. Both tests are preserved and no
test logic changes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/fff_print/test_gcodewriter.cpp

@@ -1084,6 +1084,8 @@ SCENARIO("set_pressure_advance emits BBL M900 L1000 M10 regardless of tool index
             }
         }
     }
+}
+
 TEST_CASE("Custom G-code motion limits are restored before generated moves", "[GCodeWriter]")
 {
     const std::string gcode = Slic3r::Test::slice({ cube(20) }, {