updating default node runtimes

[bilindhajer]

This PR does the following,

1. Updates default node runtimes for lambdas to nodejs18.x
2. Updates cfn-lint in python dependencies to a version that recognizes that nodejs18.x is now supported, these dependencies are now specified in a separate requirements.dev.txt for better maintenance.
3. Adds Node18 to Travis Build Matrix
4. Adds AWS SDK Suppression messages to lib/validatethis also required to update aws-sdk to version 2.1425.0

This will be published as a new major version (7.0.0) since we are changing node defaults.

Internal Tests:

bilindhajer@C02DR2R4MD6T managed-emr % ./node_modules/.bin/build-template ./cloudformation/managed-emr.template.js > /dev/null
bilindhajer@C02DR2R4MD6T managed-emr % echo $?
0
bilindhajer@C02DR2R4MD6T managed-emr % ./node_modules/.bin/validate-template ./cloudformation/managed-emr.template.js
✔ valid
bilindhajer@C02DR2R4MD6T managed-emr % ./node_modules/.bin/build-template ./cloudformation/managed-emr.template.js | grep Runtime
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",
                "Runtime": "nodejs18.x",

bilindhajer@C02DR2R4MD6T managed-emr % mbx update staging -a default        
Starting update in [default:us-east-1]
   "Metadata": {
     "MbxcliVersion": "6.1.7",
     "Repository": "managed-emr",
-    "TagfriendVersion": "1.9.5"
+    "TagfriendVersion": "1.10.0"
   },
   "Outputs": {
     "ClusterRequestsByAccountDatabase": {

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

---------------------------------------------

             "Arn"
           ]
         },
-        "Runtime": "nodejs14.x",
+        "Runtime": "nodejs18.x",
         "Tags": [
           {
             "Key": "Team",

? Accept template changes? (Y/n) 

[immad-imtiaz]

PR looks good. Approved!