Add support for Node.js version 18

Node.js v18 was released on 2022-04-19¹.

¹ https://github.com/nodejs/Release/blob/54e615d89bf2e056644e138e7e33714bfd1b67ee/README.md#release-schedule

.github/workflows/ci.yaml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -37,7 +37,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -50,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
@@ -62,7 +62,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [12, 14, 16]
+        node: [12, 14, 16, 18]
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2

package.json

@@ -7,7 +7,7 @@
   "repository": "github:nextstrain/auspice",
   "homepage": "https://www.npmjs.com/package/auspice",
   "engines": {
-    "node": "^12 || ^14 || ^16",
+    "node": "^12 || ^14 || ^16 || ^18",
     "npm": "^7 || ^8"
   },
   "bin": {