build(cmake): isolate test-only dependencies

tests/unit/core/version_test.cpp

@@ -0,0 +1,11 @@
+#include <gtest/gtest.h>
+
+#include <fesa/core/version.hpp>
+
+namespace {
+
+TEST(Version, ReportsPhaseOneSemanticVersion) {
+    EXPECT_EQ(fesa::version(), "0.1.0");
+}
+
+}  // namespace