chore:(deps): bump bootstrap from 4.5.2 to 4.5.3 in /explorer (#12872)

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 4.5.2 to 4.5.3.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](https://github.com/twbs/bootstrap/compare/v4.5.2...v4.5.3)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

explorer/package-lock.json

@@ -5101,9 +5101,9 @@
       "integrity": "sha1-aN/1++YMUes3cl6p4+0xDcwed24="
     },
     "bootstrap": {
-      "version": "4.5.2",
-      "resolved": "https://registry.npmjs.org/bootstrap/-/bootstrap-4.5.2.tgz",
-      "integrity": "sha512-vlGn0bcySYl/iV+BGA544JkkZP5LB3jsmkeKLFQakCOwCM3AOk7VkldBz4jrzSe+Z0Ezn99NVXa1o45cQY4R6A=="
+      "version": "4.5.3",
+      "resolved": "https://registry.npmjs.org/bootstrap/-/bootstrap-4.5.3.tgz",
+      "integrity": "sha512-o9ppKQioXGqhw8Z7mah6KdTYpNQY//tipnkxppWhPbiSWdD+1raYsnhwEZjkTHYbGee4cVQ0Rx65EhOY/HNLcQ=="
     },
     "brace-expansion": {
       "version": "1.1.11",

explorer/package.json

@@ -22,7 +22,7 @@
     "@types/react-select": "^3.0.22",
     "@types/socket.io-client": "^1.4.34",
     "bn.js": "^5.1.3",
-    "bootstrap": "^4.5.2",
+    "bootstrap": "^4.5.3",
     "bs58": "^4.0.1",
     "chai": "^4.2.0",
     "chart.js": "^2.9.3",