pascals-triangle: format each row as one line (#1996)

suggested as a follow-up action to format-array being merged, on at
least two separate occasions:

#1968 (comment)
#1966 (comment)

The reason for the suggestion is that helps visualise the human-readable
form of the triangle that we are used to seeing.

Author: petertseng

bin/format-array.rb

@@ -61,6 +61,9 @@
   'ocr-numbers' => {
     'rows' => :multi_line,
   },
+  'pascals-triangle' => {
+    'expected' => :multi_line,
+  },
   'rectangles' => {
     'strings' => :multi_line_unless_single,
   },

exercises/pascals-triangle/canonical-data.json

@@ -21,7 +21,9 @@
       "input": {
         "count": 1
       },
-      "expected": [[1]]
+      "expected": [
+        [1]
+      ]
     },
     {
       "uuid": "a6e5a2a2-fc9a-4b47-9f4f-ed9ad9fbe4bd",
@@ -30,7 +32,10 @@
       "input": {
         "count": 2
       },
-      "expected": [[1], [1, 1]]
+      "expected": [
+        [1],
+        [1, 1]
+      ]
     },
     {
       "uuid": "97206a99-79ba-4b04-b1c5-3c0fa1e16925",
@@ -39,7 +44,11 @@
       "input": {
         "count": 3
       },
-      "expected": [[1], [1, 1], [1, 2, 1]]
+      "expected": [
+        [1],
+        [1, 1],
+        [1, 2, 1]
+      ]
     },
     {
       "uuid": "565a0431-c797-417c-a2c8-2935e01ce306",
@@ -48,7 +57,12 @@
       "input": {
         "count": 4
       },
-      "expected": [[1], [1, 1], [1, 2, 1], [1, 3, 3, 1]]
+      "expected": [
+        [1],
+        [1, 1],
+        [1, 2, 1],
+        [1, 3, 3, 1]
+      ]
     },
     {
       "uuid": "06f9ea50-9f51-4eb2-b9a9-c00975686c27",
@@ -57,7 +71,13 @@
       "input": {
         "count": 5
       },
-      "expected": [[1], [1, 1], [1, 2, 1], [1, 3, 3, 1], [1, 4, 6, 4, 1]]
+      "expected": [
+        [1],
+        [1, 1],
+        [1, 2, 1],
+        [1, 3, 3, 1],
+        [1, 4, 6, 4, 1]
+      ]
     },
     {
       "uuid": "c3912965-ddb4-46a9-848e-3363e6b00b13",