Remove support for Node.js version 14

Node.js v14 went from LTS to end-of-life status on 2023-04-30¹.

Both of our internal consumers of auspice (auspice.us, nextstrain) use
node v16.

This commit parallels 402828c (2023-03-03) which removed support for
node v12.

¹ https://github.com/nodejs/release#release-schedule

.github/workflows/ci.yaml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16, 18]
+        node: [16, 18]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
@@ -26,7 +26,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16, 18]
+        node: [16, 18]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16, 18]
+        node: [16, 18]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3
@@ -57,7 +57,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [14, 16, 18]
+        node: [16, 18]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3

package.json

@@ -7,7 +7,7 @@
   "repository": "github:nextstrain/auspice",
   "homepage": "https://www.npmjs.com/package/auspice",
   "engines": {
-    "node": "^14 || ^16 || ^18",
+    "node": "^16 || ^18",
     "npm": "^7 || ^8 || ^9"
   },
   "bin": {