Bump @11ty/eleventy-img from 3.1.6 to 3.1.8 (#3751)

Bumps [@11ty/eleventy-img](https://github.com/11ty/eleventy-img) from 3.1.6 to 3.1.8.
- [Release notes](https://github.com/11ty/eleventy-img/releases)
- [Commits](11ty/eleventy-img@v3.1.6...v3.1.8)

---
updated-dependencies:
- dependency-name: "@11ty/eleventy-img"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: John Skiles Skinner <john.skinner@gsa.gov>

package.json

@@ -20,7 +20,7 @@
   "license": "CC0-1.0",
   "dependencies": {
     "@11ty/eleventy": "^2.0.1",
-    "@11ty/eleventy-img": "^3.1.6",
+    "@11ty/eleventy-img": "^3.1.8",
     "@uswds/uswds": "^3.6.1",
     "autoprefixer": "^10.4.16",
     "eleventy-plugin-svg-sprite": "^2.4.2",