ci/cd: Disable Fedora 30 due to missing ipython package

Error message:

$ dnf install gcc gcc-c++ python python-devel ccache gsl gsl-devel libgcrypt gtk3 gtk3-devel sqlite sqlite-devel libxml2 libxml2-devel openmpi openmpi-devel boost-devel pygobject3-devel python3-gobject gobject-introspection-devel goocanvas2-devel graphviz-devel graphviz ipython --assumeyes
Fedora Modular 30 - x86_64                      3.2 MB/s | 2.7 MB     00:00
Fedora Modular 30 - x86_64 - Updates            4.8 MB/s | 4.1 MB     00:00
Fedora 30 - x86_64 - Updates                    9.0 MB/s |  24 MB     00:02
Fedora 30 - x86_64                              9.9 MB/s |  70 MB     00:07
Package libgcrypt-1.8.5-1.fc30.x86_64 is already installed.
Package libxml2-2.9.9-2.fc30.x86_64 is already installed.
No match for argument: ipython
Error: Unable to find a match: ipython

From https://gitlab.com/nsnam/ns-3-dev/-/jobs/535839400

The funny thing is that the same line works for Fedora 29 and 31.

utils/tests/gitlab-ci-fedora.yml

@@ -75,24 +75,24 @@ weekly-build-fedora-29-optimized:
   variables:
     MODE: optimized
 
-# Fedora 30
-weekly-build-fedora-30-debug:
-  extends: .weekly-build-fedora
-  image: fedora:30
-  variables:
-    MODE: debug
+# Fedora 30 -- DISABLED BECAUSE OF MISSING iphyton
+#weekly-build-fedora-30-debug:
+#  extends: .weekly-build-fedora
+#  image: fedora:30
+#  variables:
+#    MODE: debug
 
-weekly-build-fedora-30-release:
-  extends: .weekly-build-fedora
-  image: fedora:30
-  variables:
-    MODE: release
+#weekly-build-fedora-30-release:
+#  extends: .weekly-build-fedora
+#  image: fedora:30
+#  variables:
+#    MODE: release
 
-weekly-build-fedora-30-optimized:
-  extends: .weekly-build-fedora
-  image: fedora:30
-  variables:
-    MODE: optimized
+#weekly-build-fedora-30-optimized:
+#  extends: .weekly-build-fedora
+#  image: fedora:30
+#  variables:
+#    MODE: optimized
 
 # Fedora 31
 weekly-build-fedora-31-debug: