Add framework for executing tests against multiple postgresql versions using docker compose.

tests/pgintegration/CMakeLists.txt

@@ -0,0 +1,21 @@
+add_library(pgintegration STATIC
+    PgTestEnvironment.h
+    PgTestEnvironment.cpp
+    DbTest.h
+    DbTest.cpp
+    )
+
+target_link_libraries(pgintegration PUBLIC
+    pgsql
+    GTest::gtest
+    Qt6::Core
+    )
+
+target_include_directories(pgintegration PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    )
+
+set_target_properties(pgintegration PROPERTIES
+    CXX_STANDARD 20
+    CXX_STANDARD_REQUIRED ON
+    )