### Increase the Kubernetes support window to one year

As of Kubernetes 1.19, bugfix support via patch releases for a Kubernetes minor release has increased from 9 months to 1 year.

A survey conducted in early 2019 by the working group (WG) Long Term Support (LTS) showed that a significant subset of Kubernetes end-users fail to upgrade within the previous 9-month support period. 

    *   Add `tf.keras.layers.AbstractRNNCell` as the preferred implementation
        for RNN cells in TF v2. User can use it to implement RNN cells with
        custom behavior.
    *   Keras training and validation curves are shown on the same plot when
        using the TensorBoard callback.
    *   Switched Keras `fit/evaluate/predict` execution to use only a single
        unified path by default unless eager execution has been explicitly

pkg context, type CancelCauseFunc func(error) #51365
pkg crypto/ecdh, func P256() Curve #52221
pkg crypto/ecdh, func P384() Curve #52221
pkg crypto/ecdh, func P521() Curve #52221
pkg crypto/ecdh, func X25519() Curve #52221
pkg crypto/ecdh, method (*PrivateKey) Bytes() []uint8 #52221
pkg crypto/ecdh, method (*PrivateKey) Curve() Curve #52221
pkg crypto/ecdh, method (*PrivateKey) ECDH(*PublicKey) ([]uint8, error) #52221

275F..2760    ; valid                  ;      ; NV8    # 6.0  HEAVY LOW SINGLE COMMA QUOTATION MARK ORNAMENT..HEAVY LOW DOUBLE COMMA QUOTATION MARK ORNAMENT
2761..2767    ; valid                  ;      ; NV8    # 1.1  CURVED STEM PARAGRAPH SIGN ORNAMENT..ROTATED FLORAL HEART BULLET
2768..2775    ; valid                  ;      ; NV8    # 3.2  MEDIUM LEFT PARENTHESIS ORNAMENT..MEDIUM RIGHT CURLY BRACKET ORNAMENT