Make sure version in x-changedInMatrixVersion is a string (#1562)

data/event-schemas/schema/m.call.hangup.yaml

@@ -35,7 +35,7 @@ properties:
           previous previous versions of the spec, so a missing value should be
           treated as `user_hangup`.
         x-changedInMatrixVersion:
-          1.7: |-
+          "1.7": |-
             Additional values were added.
         enum:
         - ice_timeout

data/event-schemas/schema/m.receipt.yaml

@@ -2,7 +2,7 @@ type: object
 title: Receipt Event
 description: Informs the client of new receipts.
 x-changedInMatrixVersion:
-    1.4: |
+    "1.4": |
         Added `m.read.private` receipts to the event's `content`.
 allOf:
     - $ref: "core-event-schema/event.yaml"

data/event-schemas/schema/m.room.encrypted.yaml

@@ -42,7 +42,7 @@ properties:
       sender_key:
         type: string
         x-changedInMatrixVersion:
-          1.3: |-
+          "1.3": |-
             Previously this field was required, however given it offers no additional
             security or privacy benefit it has been deprecated for Megolm messages.
             See [`m.megolm.v1.aes-sha2`](#mmegolmv1aes-sha2) for more information.
@@ -57,7 +57,7 @@ properties:
       device_id:
         type: string
         x-changedInMatrixVersion:
-          1.3: |-
+          "1.3": |-
             Previously this field was required for Megolm messages, however given it
             offers no additional security or privacy benefit it has been deprecated
             for Megolm messages. See [`m.megolm.v1.aes-sha2`](#mmegolmv1aes-sha2) for

data/event-schemas/schema/m.room_key_request.yaml

@@ -24,7 +24,7 @@ properties:
           sender_key:
             type: string
             x-changedInMatrixVersion:
-              1.3: |-
+              "1.3": |-
                 Previously this field was required, however given it offers no additional
                 security or privacy benefit it has been deprecated. See [`m.megolm.v1.aes-sha2`](#mmegolmv1aes-sha2)
                 for more information.