Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -329,6 +329,7 @@ _**Note:** Our group is currently taking a break from grinding leetcode. The tab
 | May 12, 2025 | [2094](https://leetcode.com/problems/finding-3-digit-even-numbers/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2094) | 🟢 Easy |
 | May 13, 2025 | [3335](https://leetcode.com/problems/total-characters-in-string-after-transformations-i/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3335) | 🟡 Medium |
 | May 14, 2025 | [3337](https://leetcode.com/problems/total-characters-in-string-after-transformations-ii/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3337) | 🔴 Hard |
+| May 15, 2025 | [2900](https://leetcode.com/problems/longest-unequal-adjacent-groups-subsequence-i/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2900) | 🟢 Easy |
 
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