Fix code expecting what() to return a string_view

Author: Krzmbrzl

tests/unit/test_macros.cpp

@@ -22,7 +22,8 @@ sequant::assert_failed("test");
       // initialized as default argument see
       // https://github.com/llvm/llvm-project/issues/56379
 #if !defined(SEQUANT_CXX_COMPILER_IS_CLANG) || __clang_major__ >= 16
-      REQUIRE(ex.what().find("tests/unit/test_macros.cpp:1000 in function ") !=
+      REQUIRE(std::string_view(ex.what()).find(
+                  "tests/unit/test_macros.cpp:1000 in function ") !=
               std::string::npos);
 #endif
     }
@@ -37,7 +38,8 @@ SEQUANT_ASSERT(1 == 0 && "1 != 0", "testing SEQUANT_ASSERT");
       // initialized as default argument see
       // https://github.com/llvm/llvm-project/issues/56379
 #if defined(SEQUANT_CXX_COMPILER_IS_CLANG) && __clang_major__ >= 16
-      REQUIRE(ex.what().find("tests/unit/test_macros.cpp:2000 in function ") !=
+      REQUIRE(std::string_view(ex.what()).find(
+                  "tests/unit/test_macros.cpp:2000 in function ") !=
               std::string::npos);
 #endif
     }