Fix invalid encoding name

[miyucy]

Found an incorrect setting in the database encoding pragma that could potentially cause character encoding issues.

irb(main):012> a = SQLite3::Database.new(":memoery:")
=>
#<SQLite3::Database:0x000000011f6b5330
...
irb(main):013> a.encoding = "utf-16be "
/app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/statement.rb:36:in `prepare': unsupported encoding: UTF-16BE : (SQLite3::SQLException)
PRAGMA encoding='UTF-16BE '
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/statement.rb:36:in `initialize'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:170:in `new'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:170:in `prepare'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:202:in `execute'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/pragmas.rb:65:in `set_enum_pragma'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/pragmas.rb:230:in `encoding='
        from (irb):13:in `<main>'
        from <internal:kernel>:187:in `loop'
        from <internal:prelude>:5:in `irb'
        from (app):16:in `<main>'
irb(main):014> a.encoding = "utf-16be"
/app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/pragmas.rb:63:in `set_enum_pragma': unrecognized encoding "utf-16be" (SQLite3::Exception)
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/pragmas.rb:230:in `encoding='
        from (irb):14:in `<main>'
        from <internal:kernel>:187:in `loop'
        from <internal:prelude>:5:in `irb'
        from (app):16:in `<main>'
irb(main):015> a.execute("pragma encoding='UTF-16BE '")
/app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/statement.rb:36:in `prepare': unsupported encoding: UTF-16BE : (SQLite3::SQLException)
pragma encoding='UTF-16BE '
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/statement.rb:36:in `initialize'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:170:in `new'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:170:in `prepare'
        from /app/vendor/bundle/ruby/3.3.0/gems/sqlite3-2.2.0-arm64-darwin/lib/sqlite3/database.rb:202:in `execute'
        from (irb):15:in `<main>'
        from <internal:kernel>:187:in `loop'
        from <internal:prelude>:5:in `irb'
        from (app):16:in `<main>'
irb(main):016> a.execute("pragma encoding='UTF-16BE'")
=> []

[flavorjones]

@miyucy Thank you for this! It's been broken since #encoding= was introduced.

I added a commit with new test coverage for Database#encoding= and a changelog entry.