Update ArduinoJson to v7

Author: renovate[bot]

variants/nrf52840/heltec_mesh_solar/platformio.ini

@@ -16,7 +16,7 @@ lib_deps =
   # renovate: datasource=git-refs depName=NMIoT-meshsolar packageName=https://github.com/NMIoT/meshsolar gitBranch=main
   https://github.com/NMIoT/meshsolar/archive/dfc5330dad443982e6cdd37a61d33fc7252f468b.zip
   # renovate: datasource=custom.pio depName=ArduinoJson packageName=bblanchon/library/ArduinoJson
-  bblanchon/ArduinoJson@6.21.5
+  bblanchon/ArduinoJson@7.4.2
 
 [env:heltec-mesh-solar]
 custom_meshtastic_hw_model = 108

variants/nrf52840/rak4631_eth_gw/platformio.ini

@@ -36,7 +36,7 @@ lib_deps =
   # renovate: datasource=git-refs depName=RAK12034-BMX160 packageName=https://github.com/RAKWireless/RAK12034-BMX160 gitBranch=main
   https://github.com/RAKWireless/RAK12034-BMX160/archive/dcead07ffa267d3c906e9ca4a1330ab989e957e2.zip
   # renovate: datasource=custom.pio depName=ArduinoJson packageName=bblanchon/library/ArduinoJson
-  bblanchon/ArduinoJson@6.21.5
+  bblanchon/ArduinoJson@7.4.2
 ; If not set we will default to uploading over serial (first it forces bootloader entry by talking 1200bps to cdcacm)
 ; Note: as of 6/2013 the serial/bootloader based programming takes approximately 30 seconds
 ;upload_protocol = jlink