Add support for matching nightly-6.1 to 6.1-SNAPSHOT

Author: marcprux

action.yml

@@ -154,6 +154,10 @@ runs:
           #SWIFT_VERSION="${LATEST_SNAPSHOT}"
           # use the latest snapshot release
           SWIFT_VERSION=$(cat ~/swift-versions.txt | grep -- '-SNAPSHOT' | head -n 1)
+        elif [[ "${SWIFT_VERSION}" == nightly-* ]]; then
+          # e.g., nightly-6.1 will match 6.1-DEVELOPMENT-SNAPSHOT-*
+          SWIFT_VERSION=$(echo ${SWIFT_VERSION} | sed 's;nightly-;;g')
+          SWIFT_VERSION=$(cat ~/swift-versions.txt | grep -- "${SWIFT_VERSION}-SNAPSHOT" | head -n 1)
         else
           # match "6.0" to "6.0.3"
           # match "6.1" to "6.1-DEVELOPMENT-SNAPSHOT-2025-03-07-a"