ci: add rpm-build to Fedora base image

This is needed to test the CPack RPM generator.

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

@@ -36,6 +36,10 @@ dnf install --setopt=install_weak_deps=False -y \
     jq \
     which
 
+# Packages needed to test CPack.
+dnf install --setopt=install_weak_deps=False -y \
+    rpm-build
+
 # Packages needed to test find modules.
 dnf install --setopt=install_weak_deps=False -y \
     alsa-lib-devel \

.gitlab/os-linux.yml

@@ -69,7 +69,7 @@
 ### Fedora
 
 .fedora34:
-    image: "kitware/cmake:ci-fedora34-x86_64-2021-06-07"
+    image: "kitware/cmake:ci-fedora34-x86_64-2021-06-10"
 
     variables:
         GIT_CLONE_PATH: "$CI_BUILDS_DIR/cmake ci/long file name for testing purposes"