json: adjust definitions alias

JSON Schema suggests[1] using "$defs" rather than "definitions" as
the location for reusable definitions in a schema.  While, this
isn't strictly required, there is some implication that using it
lends to better schema validation error reporting[2].

Adjust all the schema files to use "$defs" rather than "definitions".

[1]: https://json-schema.org/understanding-json-schema/structuring#defs
[2]: https://github.com/orgs/json-schema-org/discussions/151

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I4b23890950bd2ebb7a7de99fd911fb3c9e0a4dbd
diff --git a/schemas/virtual_sensor.json b/schemas/virtual_sensor.json
index c9ba378..f4e2e5b 100644
--- a/schemas/virtual_sensor.json
+++ b/schemas/virtual_sensor.json
@@ -1,6 +1,6 @@
 {
     "$schema": "http://json-schema.org/draft-07/schema#",
-    "definitions": {
+    "$defs": {
         "VirtualSensor": {
             "title": "phosphor-virtual-sensor configuration",
             "description": "The configuration used by the virtual-sensor daemon in the phosphor-virtual-sensor repository. Virtual sensors are xyz.openbmc_project.Sensor.Value D-Bus objects that have sensor values calculated from the D-Bus sensors listed here.",
@@ -12,7 +12,7 @@
                 },
                 "MaxValue": {
                     "description": "Maximum sensor value",
-                    "$ref": "legacy.json#/definitions/Types/MaxValue"
+                    "$ref": "legacy.json#/$defs/Types/MaxValue"
                 },
                 "MinValidInput": {
                     "description": "Miniumum valid value of an input sensor",
@@ -20,7 +20,7 @@
                 },
                 "MinValue": {
                     "description": "Minimum sensor value",
-                    "$ref": "legacy.json#/definitions/Types/MinValue"
+                    "$ref": "legacy.json#/$defs/Types/MinValue"
                 },
                 "Name": {
                     "type": "string"
@@ -34,7 +34,7 @@
                 },
                 "Thresholds": {
                     "description": "Threshold values used to set and clear alarms",
-                    "$ref": "legacy.json#/definitions/Types/Thresholds"
+                    "$ref": "legacy.json#/$defs/Types/Thresholds"
                 },
                 "Type": {
                     "description": "The type of calculation this sensor uses.",
@@ -43,7 +43,7 @@
                 },
                 "Units": {
                     "description": "The sensor type, as it shows up in the D-Bus object name.",
-                    "$ref": "legacy.json#/definitions/Types/Units"
+                    "$ref": "legacy.json#/$defs/Types/Units"
                 }
             },
             "required": ["Name", "Sensors", "Type", "Units"]