Update code-cov on README

Author: cowtowncoder

README.md

@@ -28,7 +28,7 @@ Project contains versions 2.0 and above: source code for earlier (1.x) versions
 | Artifact | [![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.fasterxml.jackson.core/jackson-core/badge.svg)](https://maven-badges.herokuapp.com/maven-central/com.fasterxml.jackson.core/jackson-core) |
 | OSS Sponsorship | [![Tidelift](https://tidelift.com/badges/package/maven/com.fasterxml.jackson.core:jackson-core)](https://tidelift.com/subscription/pkg/maven-com-fasterxml-jackson-core-jackson-core?utm_source=maven-com-fasterxml-jackson-core-jackson-core&utm_medium=referral&utm_campaign=readme) |
 | Javadocs | [![Javadoc](https://javadoc.io/badge/com.fasterxml.jackson.core/jackson-core.svg)](https://javadoc.io/doc/com.fasterxml.jackson.core/jackson-core) |
-| Code coverage (2.16) | [![codecov.io](https://codecov.io/github/FasterXML/jackson-core/coverage.svg?branch=2.16)](https://codecov.io/github/FasterXML/jackson-core?branch=2.16) |
+| Code coverage (2.18) | [![codecov.io](https://codecov.io/github/FasterXML/jackson-core/coverage.svg?branch=2.18)](https://codecov.io/github/FasterXML/jackson-core?branch=2.18) |
 | CodeQ (ClusterFuzz) | [![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/jackson-core.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:jackson-core) |
 | OpenSSF Score | [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/FasterXML/jackson-core/badge)](https://securityscorecards.dev/viewer/?uri=github.com/FasterXML/jackson-core) |