package/json-for-modern-cpp: fixup the 'v' prefix in the version

In order for the json-for-modern-cpp version to match what is given by
release-monitoring.org, the 'v' prefix should be encoded in
JSON_FOR_MODERN_CPP_SITE and not JSON_FOR_MODERN_CPP_VERSION.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/json-for-modern-cpp/json-for-modern-cpp.hash

@@ -1,3 +1,3 @@
 # Locally computed
-sha256	d51a3a8d3efbb1139d7608e28782ea9efea7e7933157e8ff8184901efd8ee760	json-v3.7.0.tar.gz
+sha256	d51a3a8d3efbb1139d7608e28782ea9efea7e7933157e8ff8184901efd8ee760	json-3.7.0.tar.gz
 sha256	7400586ce89c6a2cc65f6ca46997da5d356a230673d3a211e040b783f23578a1	LICENSE.MIT

package/json-for-modern-cpp/json-for-modern-cpp.mk

@@ -4,9 +4,9 @@
 #
 ################################################################################
 
-JSON_FOR_MODERN_CPP_VERSION = v3.7.0
+JSON_FOR_MODERN_CPP_VERSION = 3.7.0
 JSON_FOR_MODERN_CPP_SOURCE = json-$(JSON_FOR_MODERN_CPP_VERSION).tar.gz
-JSON_FOR_MODERN_CPP_SITE = $(call github,nlohmann,json,$(JSON_FOR_MODERN_CPP_VERSION))
+JSON_FOR_MODERN_CPP_SITE = $(call github,nlohmann,json,v$(JSON_FOR_MODERN_CPP_VERSION))
 JSON_FOR_MODERN_CPP_LICENSE = MIT
 JSON_FOR_MODERN_CPP_LICENSE_FILES = LICENSE.MIT
 JSON_FOR_MODERN_CPP_INSTALL_STAGING = YES