feat: add accountid support; remove imdsv1 support

Author: Sean O'Brien

.changes/nextrelease/imds-updates.json

@@ -0,0 +1,7 @@
+[
+  {
+    "type": "feature",
+    "category": "Credentials",
+    "description": "Adds `InstanceProfileProvider` support for sourcing account id and removes support for imdsv1."
+  }
+]

.github/workflows/git-secrets-scan.yml

@@ -36,7 +36,7 @@ jobs:
             'src/data/s3control/2018-08-20/endpoint-tests-1.json.php'
             'src/data/dynamodb/2011-12-05/endpoint-tests-1.json.php'
             'src/data/dynamodb/2012-08-10/endpoint-tests-1.json.php'
-            'tests/DynamoDb/MarshalerTest.php'
+            'tests/DynamoDb/MarshalerTest.php',
             '- '
             '\[ERROR\]'
             '\\n'
@@ -53,6 +53,12 @@ jobs:
             '/"AccountId": "123456789012"/'
             '/"AccountId": "999999999999"/'
             '/"AccountId": "012345678901"/'
+            '/"AccessKeyId": "ASIAIOSFODNN7EXAMPLE"/'
+            '/"accountId": "314253647589"/'
+            '/"accountId": "345678910112"/'
+            '/"accountId": "234567891011"/'
+            '/"AccountId": "234567891011"/'
+            '/"AccountId": "123456789101"/'
             '/"AWS::Auth::AccountId": "012345678901"/'
             '/123456789012/'
             '/999999999999/'