Update NEWS (provisions for 6.3 release).

NEWS.md

+Announcement for Dynare 6.3
+===========================================
+
+We are pleased to announce the release of Dynare 6.3.
+
+This maintenance release fixes various bugs.
+
+The Windows, macOS, MATLAB online and source packages are available for
+download at [the Dynare website](https://www.dynare.org/download/).
+
+This release is compatible with MATLAB versions ranging from 9.5 (R2018b) to
+24.2 (R2024b), and with GNU Octave versions ranging from 7.1.0 to 9.2.0 (NB:
+the Windows package requires version 9.2.0 specifically).
+
+Here is a list of the problems identified in version 6.2 and that have been
+fixed in version 6.3:
+
+* OccBin with option `smoother_inversion_filter` would crash the MCMC estimation if the `filtered_variables` or `filter_step_ahead` options were used
+* OccBin with option `smoother_inversion_filter` would use the PKF if `mh_replic>0`
+* OccBin with option `smoothed_state_uncertainty` would crash Dynare if the MCMC smoother was run after the classical one
+* OccBin's smoother would crash when encountering an internal error due to the output of the linear smoother not having been computed
+* Calling `model_info` with `differentiate_forward_vars` would crash
+* The `identification` command would compute the asymptotic Hessian via simulation instead of via moments as intended
+* The `identification` command would crash during prior sampling if the initial draw did not solve the model
+* The `gsa_sample_file` was broken
+* Optimization algorithm `mode_compute=5` (`newrat`) would crash with `analytic_derivation`
+* `discretionary_policy` would crash if the model was purely forward-looking
+* The `dsample` command would crash
+* The `conditional_forecast_paths` block did not accept vector inputs
+* For MCMC chains with fewer than 6000 draws, the default number of `sub_draws` used to compute posterior moments was incorrect
+* Bi-annual dates (e.g. `2024S1` or `2024H1`) were not accepted within Dynare statements
+* Plotting `dseries` did not correctly show dates on the x-axis
+
+
 Announcement for Dynare 6.2 (on 2024-09-25)
 ===========================================