COMP: Update w3 gateway CID identification

w3 now has its own gateway, w3s.link.

This now make the ExternalData.cmake consistent with https://github.com/InsightSoftwareConsortium/CMakeIPFSExternalData
commit 951850d4609170d5d763143b3c142c980da32702.

Author: thewtex

CMake/ExternalData.cmake

@@ -537,8 +537,8 @@ function(_ExternalData_compute_hash var_hash algo file)
     if(NOT ${w3_put_result} EQUAL 0)
       message(FATAL_ERROR "Error while calling 'w3 put': ${w3_put_error}")
     endif()
-    string(FIND "${w3_put_output}" "https://dweb.link/ipfs/" dweb_loc)
-    math(EXPR cid_loc "${dweb_loc} + 23")
+    string(FIND "${w3_put_output}" "https://w3s.link/ipfs/" w3s_loc)
+    math(EXPR cid_loc "${w3s_loc} + 22")
     string(SUBSTRING "${w3_put_output}" ${cid_loc} -1 w3_cid)
     set("${var_hash}" "${w3_cid}" PARENT_SCOPE)
   elseif("${algo}" MATCHES "^${_ExternalData_REGEX_ALGO}$")
@@ -1126,10 +1126,10 @@ if("${ExternalData_ACTION}" STREQUAL "fetch")
   string(REPLACE "+" ";" exts_list "${exts}")
   set(succeeded 0)
   set(errorMsg "")
-  set(hash_list)
-  set(algo_list)
-  set(hash)
-  set(algo)
+  set(hash_list )
+  set(algo_list )
+  set(hash )
+  set(algo )
   foreach(ext ${exts_list})
     file(READ "${name}${ext}" hash)
     string(STRIP "${hash}" hash)