Fix erroneous agm_elliptic_perimeter if radius y > radius x #742

Job	Run time
cargo clippy (wasm32)	54s
cargo check (msrv) (wasm32)	21s
cargo check (msrv) (windows-latest)	57s
cargo clippy (windows-latest)	1m 19s
cargo check (msrv) (macos-latest)	27s
cargo clippy (macos-latest)	38s
cargo doc	24s
cargo check (msrv) (ubuntu-latest)	20s
formatting	24s
cargo clippy (ubuntu-latest)	48s
cargo test (windows-latest)	53s
cargo test (wasm32)	17s
typos	4s
cargo test (macos-latest)	24s
cargo test (ubuntu-latest)	19s
	8m 29s

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