Download Eigen over HTTPS rather than plain HTTP

Author: Jordan08

CMakeLists.txt

@@ -138,7 +138,11 @@
     message(STATUS "Found Eigen3 version ${Eigen3_VERSION} in ${Eigen3_DIR}")
   else()
     message(STATUS "Attempt to install custom Eigen3 automatically...")
-    FetchContent_Declare(Eigen3 URL http://github.com/codac-team/eigen/archive/refs/heads/eigen-5.0.zip)
+    # Over HTTPS, not plain HTTP: the connections to port 80 of github.com timed
+    # out now and then on the GitHub Actions runners, failing the whole job at
+    # configuration time ("Failed to connect to github.com port 80"), and HTTPS
+    # also guarantees that the archive comes from GitHub unaltered.
+    FetchContent_Declare(Eigen3 URL https://github.com/codac-team/eigen/archive/refs/heads/eigen-5.0.zip)
     #FetchContent_Declare(Eigen3 URL ${CMAKE_CURRENT_SOURCE_DIR}/3rd/eigen-a0dc3994bd5d4e804dab58decb78c56a5af516ba.zip) # If needed to be self-contained...
     FetchContent_MakeAvailable(Eigen3)
   endif()