[ci] Add also ROOT 6.26 and 6.30 from LCG to the test matrix

This is to test also these older ROOT versions with the more rigurous
CTests that come when building Combine standalone with CMake.

Author: guitargeek

.github/workflows/cvmfs-ci.yml

@@ -31,6 +31,18 @@ jobs:
             CMSSW_VERSION: "CMSSW_14_0_0_pre1"
             SCRAM_ARCH: "el9_amd64_gcc12"
             ROOT: "6.26.11"
+          - LCG_RELEASE: "LCG_102"
+            LCG_ARCH: "x86_64-ubuntu2204-gcc11-opt"
+            ROOT: "6.26.04"
+          # Nobody is using Combine with ROOT 6.28 because this ROOT version
+          # was not used in CMSSW. But if you want to test it in the CI, here
+          # is how it would work:
+          # - LCG_RELEASE: "LCG_104"
+          #   LCG_ARCH: "x86_64-ubuntu2204-gcc11-opt"
+          #   ROOT: "6.28.04"
+          - LCG_RELEASE: "LCG_105"
+            LCG_ARCH: "x86_64-ubuntu2204-gcc11-opt"
+            ROOT: "6.30.02"
           - LCG_RELEASE: "LCG_106"
             LCG_ARCH: "x86_64-ubuntu2204-gcc11-opt"
             ROOT: "6.32.02"