[LibCURL_jll] Add major extension to SONAME (#48758)

We should be consistent in the SONAMEs we use when loading, so that we are properly declaring the ABI we support when loading `libcurl`.

Author: staticfloat

stdlib/LibCURL_jll/src/LibCURL_jll.jl

@@ -23,7 +23,7 @@ if Sys.iswindows()
 elseif Sys.isapple()
     const libcurl = "@rpath/libcurl.4.dylib"
 else
-    const libcurl = "libcurl.so"
+    const libcurl = "libcurl.so.4"
 end
 
 function __init__()