chore: remove unused XE_GRAPH_URL constant from scrapers/xe.py

[devin-ai-integration]

chore: remove unused XE_GRAPH_URL constant from scrapers/xe.py

Summary

Removes the unused XE_GRAPH_URL module-level constant from scrapers/xe.py. This midmarket converter API URL was speculatively defined during initial code generation but is never referenced in any scraper method. The sibling constants XE_RATE_URL and XE_SEND_MONEY_URL remain, as they are actively used by _get_rate_from_page() and _get_send_money_quote() respectively.

Review & Testing Checklist for Human

• Verify via repo-wide grep that XE_GRAPH_URL is not referenced anywhere (including dynamic/string-based lookups or external consumers importing it)

Notes

• Candidate ID: 7e788a42545c
• Devin Session
• Requested by: bot_apk

[devin-ai-integration]

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