added july 3 problem to README table

Author: paxtonfitzpatrick

README.md

@@ -8,6 +8,7 @@ Each day (ideally) we'll attempt the daily [leetcode](https://leetcode.com) prob
 |--------------|-------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|------------|
 | July 1, 2024 | [350](https://leetcode.com/problems/intersection-of-two-arrays-ii/)                                         | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/350)                     | Easy       |
 | July 2, 2024 | [1509](https://leetcode.com/problems/minimum-difference-between-largest-and-smallest-value-in-three-moves/) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/1509)                    | Medium     |
+| July 3, 2024 | [2181](https://leetcode.com/problems/merge-nodes-in-between-zeros/)                                         | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2181)                    | Medium     |
 
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