ci: add compiler-rt to Fedora base image

This is needed for `clang -fsanitize=` flags.

.gitlab/ci/docker/fedora34/install_deps.sh

@@ -12,6 +12,7 @@ dnf install --setopt=install_weak_deps=False -y \
 # Install development tools.
 dnf install --setopt=install_weak_deps=False -y \
     clang-tools-extra \
+    compiler-rt \
     gcc-c++ \
     git-core \
     make

.gitlab/os-linux.yml

@@ -69,7 +69,7 @@
 ### Fedora
 
 .fedora34:
-    image: "kitware/cmake:ci-fedora34-x86_64-2021-06-03"
+    image: "kitware/cmake:ci-fedora34-x86_64-2021-06-07"
 
     variables:
         GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci/long file name for testing purposes"