vsicurl.py: fix compatibility with curl 8.13.0rc1

We wrongly formatted HTTP response header line (omitting the reason,
and foremost the space before the optional reason).
The change of https://github.com/curl/curl/pull/16520/files#diff-14c8235d370910f1781de1a00ed1957ec948e84e88fdc52db87bd4eb7c7167ffR3896
no longer tolerates this

Author: rouault

autotest/gcore/vsicurl.py

@@ -426,7 +426,7 @@ def test_vsicurl_test_redirect_with_expires(server):
     current_time = 1500
 
     def method(request):
-        response = "HTTP/1.1 302\r\n"
+        response = "HTTP/1.1 302 Found\r\n"
         response += "Server: foo\r\n"
         response += (
             "Date: "
@@ -473,7 +473,7 @@ def method(request):
                 request.end_headers()
         else:
             # After a failed attempt on a HEAD, the client should go there
-            response = "HTTP/1.1 200\r\n"
+            response = "HTTP/1.1 200 OK\r\n"
             response += "Server: foo\r\n"
             response += (
                 "Date: "
@@ -590,7 +590,7 @@ def test_vsicurl_test_redirect_x_amz(server):
     current_time = 1500
 
     def method(request):
-        response = "HTTP/1.1 302\r\n"
+        response = "HTTP/1.1 302 Found\r\n"
         response += "Server: foo\r\n"
         response += (
             "Date: "
@@ -640,7 +640,7 @@ def method(request):
                 request.end_headers()
         else:
             # After a failed attempt on a HEAD, the client should go there
-            response = "HTTP/1.1 200\r\n"
+            response = "HTTP/1.1 200 OK\r\n"
             response += "Server: foo\r\n"
             response += (
                 "Date: "
@@ -1369,7 +1369,7 @@ def test_vsicurl_test_CPL_VSIL_CURL_USE_HEAD_NO(server):
     handler.add("GET", "/test_CPL_VSIL_CURL_USE_HEAD_NO/", 404)
 
     def method(request):
-        response = "HTTP/1.1 200\r\n"
+        response = "HTTP/1.1 200 OK\r\n"
         response += "Server: foo\r\n"
         response += "Content-type: text/plain\r\n"
         response += "Content-Length: 1000000\r\n"