Upgrade deprecated runtime nodejs8.10

Author: chriscoombs

cloudformation/continuous-integration-branch-checks.yml

@@ -155,7 +155,7 @@ Resources:
     Type: 'AWS::Serverless::Function'
     Properties:
       Handler: slack_notifications.handler
-      Runtime: nodejs8.10
+      Runtime: nodejs10.x
       CodeUri: ../ci_tools
       Description: >-
         Sends message to Slack channel when branch-check builds fail

cloudformation/continuous-integration-nightly-checks.yml

@@ -151,7 +151,7 @@ Resources:
     Type: 'AWS::Serverless::Function'
     Properties:
       Handler: email_notifications.handler
-      Runtime: nodejs8.10
+      Runtime: nodejs10.x
       CodeUri: ../ci_tools
       Description: >-
         Sends emails when builds fail

cloudformation/continuous-integration-pull-request-checks.yml

@@ -202,7 +202,7 @@ Resources:
     Type: 'AWS::Serverless::Function'
     Properties:
       Handler: codecommit_pr_notifications.handler
-      Runtime: nodejs8.10
+      Runtime: nodejs10.x
       CodeUri: ../ci_tools
       Description: >-
         Comment on the CodeCommit pull request when a build is triggered and when it completes