Bump tensorflow from 1.15 to 2.6.4 in /Ch2#100

dependabot[bot] wants to merge 1 commit intomasterpractical-nlp/practical-nlp-code:masterfrom

dependabot/pip/Ch2/tensorflow-2.6.4practical-nlp/practical-nlp-code:dependabot/pip/Ch2/tensorflow-2.6.4Copy head branch name to clipboard