chore: use "yml" extension instead of "yaml"

.lintstagedrc

@@ -1,5 +1,5 @@
 {
   "*.{js,json,md,sol,ts,yaml,yml}": [
-    "prettier --config ./.prettierrc.yaml --write"
+    "prettier --config ./.prettierrc.yml --write"
   ]
 }

package.json

@@ -77,12 +77,12 @@
     "deploy": "hardhat deploy:Greeter",
     "lint": "yarn lint:sol && yarn lint:ts && yarn prettier:check",
     "lint:sol": "solhint --config ./.solhint.json --max-warnings 0 \"contracts/**/*.sol\"",
-    "lint:ts": "eslint --config ./.eslintrc.yaml --ignore-path ./.eslintignore --ext .js,.ts .",
+    "lint:ts": "eslint --config ./.eslintrc.yml --ignore-path ./.eslintignore --ext .js,.ts .",
     "postinstall": "husky install",
     "postpublish": "pinst --enable",
     "prepublishOnly": "pinst --disable",
-    "prettier": "prettier --config ./.prettierrc.yaml --write \"**/*.{js,json,md,sol,ts,yaml,yml}\"",
-    "prettier:check": "prettier --check --config ./.prettierrc.yaml \"**/*.{js,json,md,sol,ts,yaml,yml}\"",
+    "prettier": "prettier --config ./.prettierrc.yml --write \"**/*.{js,json,md,sol,ts,yaml,yml}\"",
+    "prettier:check": "prettier --check --config ./.prettierrc.yml \"**/*.{js,json,md,sol,ts,yaml,yml}\"",
     "test": "hardhat test",
     "typechain": "cross-env TS_NODE_TRANSPILE_ONLY=true hardhat typechain"
   }