[bugfix][ci] use clang with std 17 by selecting 20.

.gitlab-ci.yml

@@ -40,8 +40,8 @@ ubuntu-20.04-clang-10-17:
   script:
     - duneci-standard-test
   variables:
-    DUNECI_TOOLCHAIN:  clang-10-17
-    DUNE_CONTROL_PATH:  /duneci/modules:$CI_PROJECT_DIR
+    DUNECI_TOOLCHAIN:  clang-10-20
+    DUNE_CONTROL_PATH: /duneci/modules:$CI_PROJECT_DIR
     #DUNE_CMAKE_FLAGS:   "-DDUNE_ENABLE_PYTHONBINDINGS=OFF -DDUNE_MAX_TEST_CORES=4 -DBUILD_SHARED_LIBS=TRUE -DDUNE_PYTHON_INSTALL_LOCATION=none -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_LATEX=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Alberta=TRUE -DCMAKE_DISABLE_FIND_PACKAGE_Vc=TRUE -DCMAKE_DISABLE_DOCUMENTATION=TRUE"
   tags: [stuttgart1]
 
@@ -51,5 +51,5 @@ ubuntu-20.04-gcc-9-17:
     - duneci-standard-test
   variables:
     DUNECI_TOOLCHAIN:  gcc-9-17
-    DUNE_CONTROL_PATH:  /duneci/modules:$CI_PROJECT_DIR
+    DUNE_CONTROL_PATH: /duneci/modules:$CI_PROJECT_DIR
   tags: [stuttgart1]