Update CHANGELOG: Fix handling of duplicate terms in SparsePolynomial #3198

Job	Run time
Check Documentation	22s
Test (stable)	23s
Test (nightly)	29s
Check (stable)	12s
Check no_std	26s
Check (nightly)	29s
List directories for parallelizing tests	5s
Check Style	4s
Test assembly	37s
Test (cp6_782/)	6s
Test (mnt4_753/)	12s
Test (mnt6_753/)	11s
Test (./ed_on_bn254)	25s
Test (./ed_on_bls12_381_bandersnatch)	20s
Test (./mnt4_298)	1s
Test (./ed_on_bls12_381)	26s
Test (./ed_on_cp6_782)	18s
Test (./vesta)	1s
Test (./bls12_381)	39s
Test (./ed_on_mnt4_753)	19s
Test (./curve25519)	26s
Test (./pallas)	1s
Test (./ed_on_bw6_761)	22s
Test (./grumpkin)	1s
Test (./secp256r1)	1s
Test (./secp256k1)	1s
Test (./secp384r1)	1s
Test (./bn254)	25s
Test (./bw6_761)	25s
Test (./ed_on_bls12_377)	24s
Test (./bw6_767)	25s
Test (./bls12_377)	36s
Test (./ed_on_mnt4_298)	1s
Test (./secq256k1)	1s
Test (./ed25519)	1s
Test (./mnt6_298)	1s
	9m 17s

Provide feedback