Add Densha de Go! 64 English v1.03 hash

[djjohnson13p]

Fixes #29.

Adds the missing Densha de Go! 64 English v1.03 patched ROM MD5 entry to N64-database.txt.

Added entry:

91131a1bb91aa42d3e8f2aa55948041f ntsc|cic5167|eeprom2k|rpak|tpak # Densha de Go! 64 (English v 1.03)

The existing v1.01 entry is preserved unchanged.

Verification performed:

• confirmed the v1.03 MD5 was not already present
• confirmed the new MD5 appears exactly once
• verified the MD5 against RetroAchievements RAHashes, which maps it to Densha de Go! 64 (Japan) [T-En by Zoinkity v1.03].z64
• kept the same MiSTer attributes as the existing accepted v1.01 English patch entry: ntsc|cic5167|eeprom2k|rpak|tpak
• confirmed Densha base fallback uses eeprom2k|rpak
• git diff --check
• git diff --cached --check
• git show --check HEAD

Only N64-database.txt is changed.